| Records |
| Author |
Schattschneider, P.; Schaffer, B.; Ennen, I.; Verbeeck, J. |
| Title |
Mapping spin-polarized transitions with atomic resolution |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
85 |
Issue |
13 |
Pages |
134422-134422,8 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
The coupling of angstrom-sized electron probes with spin-polarized electronic transitions shows that the inelastically scattered probe electron is in a mixed state containing electron vortices with nonzero orbital angular momentum. These electrons create an asymmetric intensity distribution in energy filtered diffraction patterns, giving access to maps of the magnetic moments with atomic resolution. A feasibility experiment shows evidence of the predicted effect. Potential applications are column-by-column maps of magnetic ordering, and the creation of angstrom-sized free electrons with orbital angular momentum by inelastic scattering in a thin ferromagnetic foil. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
|
| Language |
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Wos  |
000302608100004 |
Publication Date |
2012-04-11 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
41 |
Open Access |
|
| Notes |
The authors thank A. Bleloch, S. Loffler, and P. Nellist for fruitful discussions and suggestions. P.S. acknowledges financial support from the Austrian Science Fund, Project No. I543-N20. The support of the EPSRC for the SuperSTEM facility is gratefully acknowledged. J.V. acknowledges support from the European Research Council under the 7th Framework Program (FP7), ERC Grant No. 246791-COUNTATOMS and ERC Starting Grant No. 278510-VORTEX. ECASJO_; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:97390UA @ admin @ c:irua:97390 |
Serial |
1945 |
| Permanent link to this record |
| |
|
| |
| Author |
Clem, J.R.; Mawatari, Y.; Berdiyorov, G.R.; Peeters, F.M. |
| Title |
Predicted field-dependent increase of critical currents in asymmetric superconducting nanocircuits |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
85 |
Issue |
14 |
Pages |
144511-144511,16 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
The critical current of a thin superconducting strip of width W much larger than the Ginzburg-Landau coherence length xi but much smaller than the Pearl length Lambda = 2 lambda(2)/d is maximized when the strip is straight with defect-free edges. When a perpendicular magnetic field is applied to a long straight strip, the critical current initially decreases linearly with H but then decreases more slowly with H when vortices or antivortices are forced into the strip. However, in a superconducting strip containing sharp 90 degrees or 180 degrees turns, the zero-field critical current at H = 0 is reduced because vortices or antivortices are preferentially nucleated at the inner corners of the turns, where current crowding occurs. Using both analytic London-model calculations and time-dependent Ginzburg-Landau simulations, we predict that in such asymmetric strips the resulting critical current can be increased by applying a perpendicular magnetic field that induces a current-density contribution opposing the applied current density at the inner corners. This effect should apply to all turns that bend in the same direction. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
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Wos |
000302611100004 |
Publication Date |
2012-04-10 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
40 |
Open Access |
|
| Notes |
; This research, supported in part by the US Department of Energy, Office of Basic Energy Science, Division of Materials Sciences and Engineering, was performed in part at the Ames Laboratory, which is operated for the US Department of Energy by Iowa State University under Contract No. DE-AC02-07CH11358. This work also was supported in part by the Flemish Science Foundation (FWO-Vlaanderen) and the Belgian Science Policy (IAP). G.R.B. acknowledges individual support from FWO-Vlaanderen. ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:98263 |
Serial |
2695 |
| Permanent link to this record |
| |
|
| |
| Author |
Shakouri, K.; Szafran, B.; Esmaeilzadeh, M.; Peeters, F.M. |
| Title |
Effective spin-orbit interaction Hamiltonian for quasi-one-dimensional quantum rings |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
85 |
Issue |
16 |
Pages |
165314-165314,8 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
The effective Hamiltonian for an electron in a quasi-one-dimensional quantum ring in the presence of spin-orbit interactions is derived. We demonstrate that, when both coupling types are simultaneously present, the effective Hamiltonian derived by the lowest-radial-state approximation produces energy spectra and charge densities which deviate strongly from the exact ones. For equal Rashba and Dresselhaus coupling constants the lowest-radial-state approximation opens artifactal avoided crossings in the energy spectra and deforms the circular symmetry of the confined charge densities. In this case, there does not exist a ring thin enough to justify the restriction to the lowest radially quantized energy state. We derive the effective Hamiltonian accounting for both the lowest and the first excited radial states, and show that the inclusion of the latter restores the correct features of the exact solution. Relation of this result to the states of a quantum wire is also discussed. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000303068800006 |
Publication Date |
2012-04-20 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
32 |
Open Access |
|
| Notes |
; This work was partially supported by Polish Ministry of Science and Higher Education and its grants for Scientific Research. ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:98258 |
Serial |
855 |
| Permanent link to this record |
| |
|
| |
| Author |
Govaerts, K.; Sluiter, M.H.F.; Partoens, B.; Lamoen, D. |
| Title |
Stability of Sb-Te layered structures : first-principles study |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
85 |
Issue |
14 |
Pages |
144114-144114,8 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
| Abstract |
Using an effective one-dimensional cluster expansion in combination with first-principles electronic structure calculations we have studied the energetics and electronic properties of Sb-Te layered systems. For a Te concentration between 0 and 60 at. % an almost continuous series of metastable structures is obtained consisting of consecutive Sb bilayers next to consecutive Sb2Te3 units, with the general formula (Sb-2)(n)(Sb2Te3)(m) (n, m = 1,2, ... ). Between 60 and 100 at.% no stable structures are found. We account explicitly for the weak van derWaals bonding between Sb bilayers and Sb2Te3 units by using a recently developed functional, which strongly improves the interlayer bonding distances. At T = 0 K, no evidence is found for the existence of two separate single-phase regions delta and gamma and a two-phase region delta + gamma. Metastable compounds with a Te concentration between 0 and 40 at. % are semimetallic, whereas compounds with a Te concentration between 50 and 60 at. % are semiconducting. Compounds with an odd number of Sb layers are metallic and have a much higher formation energy than those with an even number of consecutive Sb layers, thereby favoring the formation of Sb bilayers. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
|
| Language |
|
Wos |
000303115400004 |
Publication Date |
2012-04-23 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
14 |
Open Access |
|
| Notes |
Iwt; Fwo |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:98255 |
Serial |
3129 |
| Permanent link to this record |
| |
|
| |
| Author |
Lajevardipour, A.; Neek-Amal, M.; Peeters, F.M. |
| Title |
Thermomechanical properties of graphene : valence force field model approach |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Journal of physics : condensed matter |
Abbreviated Journal |
J Phys-Condens Mat |
| Volume |
24 |
Issue |
17 |
Pages |
175303-175303,8 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
Using the valence force field model of Perebeinos and Tersoff (2009 Phys. Rev. B 79 241409(R)), different energy modes of suspended graphene subjected to tensile or compressive strain are studied. By carrying out Monte Carlo simulations it is found that: (i) only for small strains (vertical bar epsilon vertical bar (sic) 0.02) is the total energy symmetrical in the strain, while it behaves completely differently beyond this threshold; (ii) the important energy contributions in stretching experiments are stretching, angle bending, an out-of-plane term, and a term that provides repulsion against pi-pi misalignment; (iii) in compressing experiments the two latter terms increase rapidly, and beyond the buckling transition stretching and bending energies are found to be constant; (iv) from stretching-compressing simulations we calculated the Young's modulus at room temperature 350 +/- 3.15 N m(-1), which is in good agreement with experimental results (340 +/- 50 N m(-1)) and with ab initio results (322-353) N m(-1); (v) molar heat capacity is estimated to be 24.64 J mol(-1) K-1 which is comparable with the Dulong-Petit value, i. e. 24.94 J mol(-1) K-1, and is almost independent of the strain; (vi) nonlinear scaling properties are obtained from height-height correlations at finite temperature; (vii) the used valence force field model results in a temperature independent bending modulus for graphene, and (viii) the Gruneisen parameter is estimated to be 0.64. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
London |
Editor |
|
| Language |
|
Wos |
000303499700012 |
Publication Date |
2012-04-05 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0953-8984;1361-648X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.649 |
Times cited |
29 |
Open Access |
|
| Notes |
; We acknowledge helpful comments by V Perebeinos, S Costamagna, A Fasolino and J H Los. This work was supported by the Flemish science foundation (FWO-Vl) and the Belgium Science Policy (IAP). ; |
Approved |
Most recent IF: 2.649; 2012 IF: 2.355 |
| Call Number |
UA @ lucian @ c:irua:99123 |
Serial |
3639 |
| Permanent link to this record |
| |
|
| |
| Author |
Chen, Y.; Shanenko, A.A.; Perali, A.; Peeters, F.M. |
| Title |
Superconducting nanofilms : molecule-like pairing induced by quantum confinement |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Journal of physics : condensed matter |
Abbreviated Journal |
J Phys-Condens Mat |
| Volume |
24 |
Issue |
18 |
Pages |
185701-185701,8 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
Quantum confinement of the perpendicular motion of electrons in single-crystalline metallic superconducting nanofilms splits the conduction band into a series of single-electron subbands. A distinctive feature of such a nanoscale multi-band superconductor is that the energetic position of each subband can vary significantly with changing nanofilm thickness, substrate material, protective cover and other details of the fabrication process. It can occur that the bottom of one of the available subbands is situated in the vicinity of the Fermi level. We demonstrate that the character of the superconducting pairing in such a subband changes dramatically and exhibits a clear molecule-like trend, which is very similar to the well-known crossover from the Bardeen-Cooper-Schrieffer regime to Bose-Einstein condensation (BCS-BEC) observed in trapped ultracold fermions. For Pb nanofilms with thicknesses of 4 and 5 monolayers (MLs) this will lead to a spectacular scenario: up to half of all the Cooper pairs nearly collapse, shrinking in the lateral size (parallel to the nanofilm) down to a few nanometers. As a result, the superconducting condensate will be a coherent mixture of almost molecule-like fermionic pairs with ordinary, extended Cooper pairs. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
London |
Editor |
|
| Language |
|
Wos |
000303500900018 |
Publication Date |
2012-04-05 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0953-8984;1361-648X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.649 |
Times cited |
26 |
Open Access |
|
| Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl). AAS thanks A Bianconi, M D Croitoru and A V Vagov for useful discussions. AAS acknowledges the hospitality and fruitful interactions with G C Strinati, P Pieri and D Neilson during his visit to the University of Camerino, supported by the School of Advanced Studies of the University of Camerino. ; |
Approved |
Most recent IF: 2.649; 2012 IF: 2.355 |
| Call Number |
UA @ lucian @ c:irua:98223 |
Serial |
3357 |
| Permanent link to this record |
| |
|
| |
| Author |
Dixit, H.; Saniz, R.; Cottenier, S.; Lamoen, D.; Partoens, B. |
| Title |
Electronic structure of transparent oxides with the Tran-Blaha modified Becke-Johnson potential |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Journal of physics : condensed matter |
Abbreviated Journal |
J Phys-Condens Mat |
| Volume |
24 |
Issue |
20 |
Pages |
205503-205503,9 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
| Abstract |
We present electronic band structures of transparent oxides calculated using the Tran-Blaha modified Becke-Johnson (TB-mBJ) potential. We studied the basic n-type conducting binary oxides In2O3, ZnO, CdO and SnO2 along with the p-type conducting ternary oxides delafossite CuXO2 (X = Al, Ga, In) and spinel ZnX2O4 (X = Co, Rh, Ir). The results are presented for calculated band gaps and effective electron masses. We discuss the improvements in the band gap determination using TB-mBJ compared to the standard generalized gradient approximation (GGA) in density functional theory (DFT) and also compare the electronic band structure with available results from the quasiparticle GW method. It is shown that the calculated band gaps compare well with the experimental and GW results, although the electron effective mass is generally overestimated. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
London |
Editor |
|
| Language |
|
Wos |
000303507100009 |
Publication Date |
2012-04-27 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0953-8984;1361-648X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.649 |
Times cited |
113 |
Open Access |
|
| Notes |
Iwt; Fwo |
Approved |
Most recent IF: 2.649; 2012 IF: 2.355 |
| Call Number |
UA @ lucian @ c:irua:98222 |
Serial |
1017 |
| Permanent link to this record |
| |
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| |
| Author |
Berdiyorov, G.R.; de Romaguera, A.R.C.; Milošević, M.V.; Doria, M.M.; Covaci, L.; Peeters, F.M. |
| Title |
Dynamic and static phases of vortices under an applied drive in a superconducting stripe with an array of weak links |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
European physical journal : B : condensed matter and complex systems |
Abbreviated Journal |
Eur Phys J B |
| Volume |
85 |
Issue |
4 |
Pages |
130-130,8 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
Static and dynamic properties of superconducting vortices in a superconducting stripe with a periodic array of weakly-superconducting (or normal metal) regions are studied in the presence of external magnetic and electric fields. The time-dependent Ginzburg-Landau theory is used to describe the electronic transport, where the anisotropy is included through the spatially-dependent critical temperature T-c. Superconducting vortices penetrating into the weak-superconducting region with smaller T-c are more mobile than the ones in the strong superconducting regions. We observe periodic entrance and exit of vortices which reside in the weak link for some short interval. The mobility of the weakly-pinned vortices can be reduced by increasing the uniform applied magnetic field leading to distinct features in the voltage vs. magnetic field response of the system. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
Berlin |
Editor |
|
| Language |
|
Wos |
000303545400013 |
Publication Date |
2012-04-20 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1434-6028;1434-6036; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
1.461 |
Times cited |
32 |
Open Access |
|
| Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl), the Belgian Science Policy (IAP), the bilateral programme between Flanders and Brazil. G.R.B. and L.C. acknowledge individual support from FWO-Vl. A.R.de C.R. acknowledges CNPq and FACEPE for financial support. ; |
Approved |
Most recent IF: 1.461; 2012 IF: 1.282 |
| Call Number |
UA @ lucian @ c:irua:98267 |
Serial |
761 |
| Permanent link to this record |
| |
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| |
| Author |
Misko, V.R.; Nori, F. |
| Title |
Magnetic flux pinning in superconductors with hyperbolic-tesselation arrays of pinning sites |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
85 |
Issue |
18 |
Pages |
184506-184506,6 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
We study magnetic flux interacting with arrays of pinning sites (APSs) placed on vertices of hyperbolic tesselations (HTs). We show that, due to the gradient in the density of pinning sites, HT APSs are capable of trapping vortices for a broad range of applied magnetic fluxes. Thus, the penetration of magnetic field in HT APSs is essentially different from the usual scenario predicted by the Bean model. We demonstrate that, due to the enhanced asymmetry of the surface barrier for vortex entry and exit, this HT APS could be used as a “capacitor” to store magnetic flux. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
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Wos |
000303653600005 |
Publication Date |
2012-05-04 |
| Series Editor |
|
Series Title |
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Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
24 |
Open Access |
|
| Notes |
; V.R.M. acknowledges support from the “Odysseus” Program of the Flemish Government & FWO-Vl, and the IAP. F.N. is partially supported by the ARO, NSF Grant No. 0726909, JSPS-RFBR Contract No. 12-02-92100, Grant-in-Aid for Scientific Research (S), MEXT Kakenhi on Quantum Cybernetics, and the JSPS via its FIRST program. ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:98224 |
Serial |
1880 |
| Permanent link to this record |
| |
|
| |
| Author |
Scarrozza, M.; Pourtois, G.; Houssa, M.; Heyns, M.; Stesmans, A. |
| Title |
Oxidation of the GaAs(001) surface : insights from first-principles calculations |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
85 |
Issue |
19 |
Pages |
195307-195307,8 |
| Keywords |
A1 Journal article; Plasma Lab for Applications in Sustainability and Medicine – Antwerp (PLASMANT) |
| Abstract |
We performed a detailed investigation of the oxidation of the technologically relevant GaAs(001)-beta 2(2x4) surface via density functional calculations. The purpose is to gain insights on the atomistic mechanisms and local bondings that underlie the degradation of the surface properties once exposed to oxygen. The study comprises the adsorption of single O atoms, through the sampling of several adsorption sites, and the subsequent formation of the O adsorbate at increasing coverage by taking into account multiple-atom adsorption. Based on the evaluation of the energetics and the structural properties of the atomistic models generated, the results here reported delineate a consistent picture of the initial stage of the surface oxidation: (i) at low coverage, in the limit of single O insertions, oxygen is incorporated on the surface forming a twofold-bridging Ga-O-As bond; (ii) at increasing coverage, as multiple O atoms are involved, this is accompanied by the formation of a threefold-coordinated bond (with two Ga and one As atoms); (iii) the latter has important implications regarding the electronic properties of the adsorbate since this O bonding may result in the formation of As dangling bonds. Moreover, a clear trend of increased energy gain for the incorporation of neighboring O atoms compared to single O insertions indicates that the formation of oxide clusters is favored over a regime of uniform oxidation. Our findings provide a detailed description of the O bonding and stress the importance of modeling the adsorption of multiple O atoms for an accurate description of the surface oxidation. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
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Wos |
000303755700006 |
Publication Date |
2012-05-08 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
15 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:99122 |
Serial |
2538 |
| Permanent link to this record |
| |
|
| |
| Author |
Li, Z.; Covaci, L.; Marsiglio, F. |
| Title |
Impact of Dresselhaus versus Rashba spin-orbit coupling on the Holstein polaron |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
85 |
Issue |
20 |
Pages |
205112-205112,5 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
We utilize an exact variational numerical procedure to calculate the ground-state properties of a polaron in the presence of Rashba and linear Dresselhaus spin-orbit coupling. We find that when the linear Dresselhaus spin-orbit coupling approaches the Rashba spin-orbit coupling, the Van Hove singularity in the density of states will be shifted away from the bottom of the band and finally disappear when the two spin-orbit couplings are tuned to be equal. The effective mass will be suppressed; the trend will become more significant for low phonon frequency. The presence of two dominant spin-orbit couplings will make it possible to tune the effective mass with more varied observables. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
|
Wos |
000303794900003 |
Publication Date |
2012-05-09 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
18 |
Open Access |
|
| Notes |
; This work was supported in part by the Natural Sciences and Engineering Research Council of Canada (NSERC), by ICORE (Alberta), by the Flemish Science Foundation (FWO-Vl), and by the Canadian Institute for Advanced Research (CIfAR). ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:99121 |
Serial |
1558 |
| Permanent link to this record |
| |
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| |
| Author |
Badalyan, S.M.; Peeters, F.M. |
| Title |
Effect of nonhomogenous dielectric background on the plasmon modes in graphene double-layer structures at finite temperatures |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
85 |
Issue |
19 |
Pages |
195444-195444,6 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
We have calculated the plasmon modes in graphene double layer structures at finite temperatures, taking into account the inhomogeneity of the dielectric background of the system. The effective dielectric function is obtained from the solution of the Poisson equation of a three-layer dielectric medium with graphene sheets located at the interfaces, separating the different materials. Due to the momentum dispersion of the effective dielectric function, the intra- and interlayer bare Coulomb interactions in the graphene double layer system acquires an additional momentum dependence-an effect that is of the order of the interlayer interaction itself. We show that the energies of the in-phase and out-of-phase plasmon modes are determined largely by different values of the spatially dependent effective dielectric function. The effect of the dielectric inhomogeneity increases with temperature, and even at high temperatures the energy shift induced by the dielectric inhomogeneity and temperature itself remains larger than the broadening of the plasmon energy dispersions due to the Landau damping. The obtained new features of the plasmon dispersions can be observed in frictional drag measurements and in inelastic light scattering and electron energy-loss spectroscopies. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000304394800011 |
Publication Date |
2012-05-23 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
67 |
Open Access |
|
| Notes |
; We thank G. Vignale for useful discussions and acknowledge support from the Flemisch Science Foundation (FWO-Fl) and the Belgian Science Policy (BELSPO). ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:98941 |
Serial |
826 |
| Permanent link to this record |
| |
|
| |
| Author |
Neek-Amal, M.; Peeters, F.M. |
| Title |
Strain-engineered graphene through a nanostructured substrate : 1 : deformations |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
85 |
Issue |
19 |
Pages |
195445-195445,11 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
Using atomistic simulations we investigate the morphological properties of graphene deposited on top of a nanostructured substrate. Sinusoidally corrugated surfaces, steps, elongated trenches, one-dimensional and cubic barriers, spherical bubbles, Gaussian bumps, and Gaussian depressions are considered as support structures for graphene. The graphene-substrate interaction is governed by van der Waals forces and the profile of the graphene layer is determined by minimizing the energy using molecular dynamics simulations. Based on the obtained optimum configurations, we found that (i) for graphene placed over sinusoidally corrugated substrates with corrugation wavelengths longer than 2 nm, the graphene sheet follows the substrate pattern while for supported graphene it is always suspended across the peaks of the substrate, (ii) the conformation of graphene to the substrate topography is enhanced when increasing the energy parameter in the van der Waals model, (iii) the adhesion of graphene into the trenches depends on the width of the trench and on the graphene's orientation, i. e., in contrast to a small-width (3 nm) nanoribbon with armchair edges, the one with zigzag edges follows the substrate profile, (iv) atomic-scale graphene follows a Gaussian bump substrate but not the substrate with a Gaussian depression, and (v) the adhesion energy due to van der Waals interaction varies in the range [0.1-0.4] J/m(2). |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
|
| Language |
|
Wos |
000304394800012 |
Publication Date |
2012-05-23 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
62 |
Open Access |
|
| Notes |
; We thank L. Covaci and S. Costamagna for valuable comments. We acknowledge M. Zarenia, M. R. Masir and D. Nasr for fruitful discussions. This work was supported by the Flemish Science Foundation (FWO-Vl) and ESF EUROCORE program EuroGRAPHENE: CONGRAN. ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:98942 |
Serial |
3166 |
| Permanent link to this record |
| |
|
| |
| Author |
Neek-Amal, M.; Peeters, F.M. |
| Title |
Strain-engineered graphene through a nanostructured substrate : 2 : pseudomagnetic fields |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
85 |
Issue |
19 |
Pages |
195446-195446,6 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
The strain-induced pseudomagnetic field in supported graphene deposited on top of a nanostructured substrate is investigated by using atomistic simulations. A step, an elongated trench, a one-dimensional barrier, a spherical bubble, a Gaussian bump, and a Gaussian depression are considered as support structures for graphene. From the obtained optimum configurations we found very strong induced pseudomagnetic fields which can reach up to similar to 1000 T due to the strain-induced deformations in the supported graphene. Different magnetic confinements with controllable geometries are found by tuning the pattern of the substrate. The resulting induced magnetic fields for graphene on top of a step, barrier, and trench are calculated. In contrast to the step and trench the middle part of graphene on top of a barrier has zero pseudomagnetic field. This study provides a theoretical background for designing magnetic structures in graphene by nanostructuring substrates. We found that altering the radial symmetry of the deformation changes the sixfold symmetry of the induced pseudomagnetic field. |
| Address |
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| Corporate Author |
|
Thesis |
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| Publisher |
|
Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000304394800013 |
Publication Date |
2012-05-23 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
31 |
Open Access |
|
| Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl) and the ESF EUROCORE program EuroGRAPHENE: CONGRAN. ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:98943 |
Serial |
3167 |
| Permanent link to this record |
| |
|
| |
| Author |
Badalyan, S.M.; Peeters, F.M. |
| Title |
Electron-phonon bound state in graphene |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
85 |
Issue |
20 |
Pages |
205453-205453,5 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
The fine structure of the Dirac energy spectrum in graphene induced by electron-optical phonon coupling is investigated in the portion of the spectrum near the phonon emission threshold. The derived new dispersion equation in the immediate neighborhood below the threshold corresponds to an electron-phonon bound state. We find that the singular vertex corrections beyond perturbation theory strongly increase the electron-phonon binding energy scale. The predicted enhancement of the effective electron-phonon coupling can be measured using angle-resolved spectroscopy. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
|
Editor |
|
| Language |
|
Wos |
000304649400002 |
Publication Date |
2012-05-30 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
12 |
Open Access |
|
| Notes |
; We thank E. Rashba for the useful discussion and acknowledge support from the Belgian Science Policy (IAP) and BELSPO. ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:98939 |
Serial |
982 |
| Permanent link to this record |
| |
|
| |
| Author |
Krstajić, P.M.; Peeters, F.M. |
| Title |
Energy-momentum dispersion relation of plasmarons in graphene |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
85 |
Issue |
20 |
Pages |
205454-205454,4 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
The many-body correction to the band structure of a quasi-free-standing graphene layer is obtained within the Overhauser approach, where the electron-plasmon interaction is described as a field theoretical problem. We find that the Dirac-like spectrum is shifted by Delta E(k = 0), which is on the order of 50-150 meV, depending on the electron concentration n(e), and is in semiquantitative agreement with experimental data. The value of the Fermi velocity is renormalized by several percents and decreases with increasing electron concentration as found experimentally. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
|
Place of Publication |
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Editor |
|
| Language |
|
Wos |
000304649900004 |
Publication Date |
2012-06-05 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
11 |
Open Access |
|
| Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl), the ESF-EuroGRAPHENE project CON-GRAN, and the Serbian Ministry of Education and Science (project No. TR 32008). ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:98937 |
Serial |
1043 |
| Permanent link to this record |
| |
|
| |
| Author |
Pogosov, W.V.; Misko, V.R. |
| Title |
Vortex quantum tunneling versus thermal activation in ultrathin superconducting nanoislands |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
85 |
Issue |
22 |
Pages |
224508-224508,5 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
We consider two possible mechanisms for single-vortex fluctuative entry/exit through the surface barrier in ultrathin superconducting disk-shaped nanoislands made of Pb and consisting of just a few monoatomic layers, which can be fabricated using modern techniques. We estimate tunneling probabilities and establish criteria for the crossover between these two mechanisms depending on magnetic field and system sizes. For the case of vortex entry, quantum tunneling dominates on the major part of the temperature/flux phase diagram. For the case of vortex exit, thermal activation turns out to be more probable. This nontrivial result is due to the subtle balance between the barrier height and width, which determine rates of the thermal activation and quantum tunneling, respectively. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
|
| Language |
|
Wos |
000304856600003 |
Publication Date |
2012-06-07 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
2 |
Open Access |
|
| Notes |
; This work was supported by the “Odysseus” Program of the Flemish Government and the Flemish Science Foundation (FWO-Vl). W. V. P. acknowledges numerous discussions with A. O. Sboychakov and the support from the Dynasty Foundation, the RFBR (Project No. 12-02-00339), and RFBR-CNRS programme (Project No. 12-02-91055). ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:98908 |
Serial |
3882 |
| Permanent link to this record |
| |
|
| |
| Author |
Singh, K.; Maignan, A.; Simon, C.; Kumar, S.; Martin, C.; Lebedev, O.; Turner, S.; Van Tendeloo, G. |
| Title |
Magnetodielectric CuCr0.5V0.5O2 : an example of a magnetic and dielectric multiglass |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Journal of physics : condensed matter |
Abbreviated Journal |
J Phys-Condens Mat |
| Volume |
24 |
Issue |
22 |
Pages |
226002-226002,4 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
The complex dielectric susceptibility and spin glass properties of polycrystalline CuCr0.5V 0.5O2 delafossite have been investigated. Electron diffraction, high resolution electron microscopy and electron energy loss spectroscopy show that the Cr3+ and V 3+ magnetic cations are randomly distributed on the triangular network of CdI2-type layers. In contrast to CuCrO2, CuCr0.5V 0.5O2 exhibits two distinctive (magnetic and electric) glassy states evidenced by memory effects in electric and magnetic susceptibilities. A large magnetodielectric coupling is observed at low temperature. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
London |
Editor |
|
| Language |
|
Wos |
000304873300027 |
Publication Date |
2012-05-02 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0953-8984;1361-648X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.649 |
Times cited |
19 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 2.649; 2012 IF: 2.355 |
| Call Number |
UA @ lucian @ c:irua:98380 |
Serial |
1916 |
| Permanent link to this record |
| |
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| |
| Author |
Čukarić, N.; Arsoski, V.; Tadić, M.; Peeters, F.M. |
| Title |
Hole states in nanocups in a magnetic field |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
85 |
Issue |
23 |
Pages |
235425-235425,11 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
The magnetic-field dependence of the hole states in a nanocup, which is composed of a ring (the nanocup rim) that surrounds a disk (the nanocup bottom), is obtained within the Luttinger-Kohn model for the unstrained GaAs/(Al,Ga) As and the strained (In,Ga) As/GaAs systems. Aharonov-Bohm oscillations due to angular momentum transitions of the hole ground state appear with periods that vary with the thickness of the disk. The strain in the (In, Ga) As/GaAs nanocup is sensitive to the disk thickness and favors the spatial localization of the heavy holes inside the disk. Therefore, the angular momentum transitions between the valence-band states disappear for much thinner disks than in the case of the unstrained GaAs/(Al, Ga) As nanocups. In both systems, the oscillations in the energy of the hole ground state are found to disappear for thinner inner layer than in the electron ground-state energy. This is due to the different confining potentials and the mixing between the heavy- and light-hole states. As a consequence, magnetization of the single hole is found to strongly depend on the bottom thickness of the strained (In, Ga) As/GaAs nanocup. Furthermore, we found that the strain can lead to a spatial separation of the electron and the hole, as in type-II band alignment, which is advantageous for the appearance of the excitonic Aharonov-Bohm effect. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
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Wos |
000305116700005 |
Publication Date |
2012-06-14 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
4 |
Open Access |
|
| Notes |
; The authors thank B. Partoens for useful discussions. This work was supported by the EU NoE: SANDiE, the Ministry of Education and Science of Serbia, and the Belgian Science Policy (IAP). ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:98906 |
Serial |
1477 |
| Permanent link to this record |
| |
|
| |
| Author |
Chen, Y.; Shanenko, A.A.; Peeters, F.M. |
| Title |
Superconducting transition temperature of Pb nanofilms : impact of thickness-dependent oscillations of the phonon-mediated electron-electron coupling |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
85 |
Issue |
22 |
Pages |
224517-224517,6 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
To date, several experimental groups reported measurements of the thickness dependence of T-c of atomically uniform single-crystalline Pb nanofilms. The reported amplitude of the T-c oscillations varies significantly from one experiment to another. Here we propose that the reason for this unresolved issue is an interplay of the quantum-size variations in the single-electron density of states with thickness-dependent oscillations in the phonon-mediated electron-electron coupling. Such oscillations in the coupling depend on the substrate material, the quality of the interface, the protection cover, and other details of the fabrication process, changing from one experiment to another. This explains why the available data do not exhibit one-voice consistency about the amplitude of the T-c oscillations. Our analyses are based on a numerical solution of the Bogoliubov-de Gennes equations for a superconducting slab. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
|
Wos |
000305251300006 |
Publication Date |
2012-06-14 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
24 |
Open Access |
|
| Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl). ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:99076 |
Serial |
3368 |
| Permanent link to this record |
| |
|
| |
| Author |
Zarenia, M.; Vasilopoulos, P.; Peeters, F.M. |
| Title |
Magnetotransport in periodically modulated bilayer graphene |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
85 |
Issue |
24 |
Pages |
245426-245426,10 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
Magnetotransport in bilayer graphene in the presence of a weak and periodic potential is investigated in the presence of a perpendicular magnetic field B. The modulation broadens the Landau levels into bands and for weak magnetic fields leads to the well-known Weiss oscillations in their bandwidth and their transport coefficients at very low B and to the Shubnikov-de Haas oscillations at larger B. The amplitude of the Weiss oscillations is severely reduced if the periodic potentials applied to the two layers oscillate out of phase. We also contrast some results with those corresponding to single-layer graphene. Relative to them the flat-band condition and the oscillation amplitude differ substantially, due to the interlayer coupling, and agree only when this coupling is extremely weak. We further show that the Hall conductivity exhibits the well-known steps at half-integer and integer multiples of 4e(2)/h in single-layer and bilayer graphene, respectively, even for very weak magnetic fields. The results are pertinent to weak and periodic corrugations when the potential modulation dominates the strain-induced magnetic modulation. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
|
Wos |
000305253600012 |
Publication Date |
2012-06-14 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
21 |
Open Access |
|
| Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl), the European Science Foundation (ESF) under the EUROCORES program EuroGRAPHENE (project CON-GRAN), and the Canadian NSERC Grant No. OGP0121756. ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:99077 |
Serial |
1934 |
| Permanent link to this record |
| |
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| |
| Author |
Tsirlin, A.A.; Abakumov, A.M.; Ritter, C.; Henry, P.F.; Janson, O.; Rosner, H. |
| Title |
Short-range order of Br and three-dimensional magnetism in (CuBr)LaNb2O7 |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
85 |
Issue |
21 |
Pages |
214427 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
We present a comprehensive study of the crystal structure, magnetic structure, and microscopic magnetic model of (CuBr)LaNb2O7, the Br analog of the spin-gap quantum magnet (CuCl) LaNb2O7. Despite similar crystal structures and spin lattices, the magnetic behavior and even peculiarities of the atomic arrangement in the Cl and Br compounds are very different. The high- resolution x-ray and neutron data reveal a split position of Br atoms in (CuBr) LaNb2O7. This splitting originates from two possible configurations developed by [CuBr] zigzag ribbons. While the Br atoms are locally ordered in the ab plane, their arrangement along the c direction remains partially disordered. The predominant and energetically more favorable configuration features an additional doubling of the c lattice parameter that was not observed in (CuCl) LaNb2O7. (CuBr) LaNb2O7 undergoes long-range antiferromagnetic ordering at T-N = 32 K, which is nearly 70% of the leading exchange coupling J4 similar or equal to 48 K. The Br compound does not show any experimental signatures of low-dimensional magnetism because the underlying spin lattice is three-dimensional. The coupling along the c direction is comparable to the couplings in the ab plane, even though the shortest Cu-Cu distance along c (11.69 angstrom) is three times larger than nearest-neighbor distances in the ab plane (3.55 angstrom). The stripe antiferromagnetic long-range order featuring columns of parallel spins in the ab plane and antiparallel spins along c is verified experimentally and confirmed by the microscopic analysis. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
|
Wos |
000305557600002 |
Publication Date |
2012-06-22 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
5 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:100289 |
Serial |
2998 |
| Permanent link to this record |
| |
|
| |
| Author |
Chen, Y.; Shanenko, A.A.; Croitoru, M.D.; Peeters, F.M. |
| Title |
Quantum cascades in nano-engineered superconductors : geometrical, thermal and paramagnetic effects |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Journal of physics : condensed matter |
Abbreviated Journal |
J Phys-Condens Mat |
| Volume |
24 |
Issue |
26 |
Pages |
265702 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
The effect of a parallel magnetic field on the orbital motion of electrons in high-quality superconducting nanowires resulting in a superconductor-to-normal transition which occurs through a cascade of jumps in the order parameter as a function of the magnetic field. Such cascades originate from the transverse size quantization that splits the conduction band into a series of subbands. Here, based on a numerical solution of the Bogoliubov-de Gennes equations for a hollow nanocylinder, we investigate how the quantum-size cascades depend on the confining geometry, i.e., by changing the cylinder radius R and its thickness d we cover the range from the nanowire-like to the nanofilm-like regime. The cascades are shown to become much less pronounced when increasing R/d, i.e., when the nanofilm-like regime is approached. When the temperature is non-zero they are thermally smoothed. This includes the spin-magnetic-field interaction which reduces the critical (depairing) parallel magnetic field H-c,H-parallel to but does not have any qualitative effect on the quantum cascades. From our calculations it is seen that the paramagnetic limiting field H-par significantly exceeds H-c,H-parallel to even in extremely narrow nanocylinders, i.e., when R, d are down to a few nanometers, and H-c,H-parallel to is only about 10% larger when switching-off the spin-magnetic-field interaction in this case. Both characteristic fields, H-c,H-parallel to and H-par, exhibit pronounced quantum-size oscillations. We demonstrate that the quantum cascades and the quantum-size oscillations survive in the presence of surface roughness. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
London |
Editor |
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| Language |
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Wos |
000305640800014 |
Publication Date |
2012-06-07 |
| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0953-8984;1361-648X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.649 |
Times cited |
6 |
Open Access |
|
| Notes |
; This work was supported by the Flemish Science Foundation (FWO-VI) and the ESF-AQDJJ network. MDC acknowledges the support of the EU Marie Curie IEF Action (Grant Agreement No. PIEF-GA-2009-235486-ScQSR). ; |
Approved |
Most recent IF: 2.649; 2012 IF: 2.355 |
| Call Number |
UA @ lucian @ c:irua:100281 |
Serial |
2773 |
| Permanent link to this record |
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| |
| Author |
Croitoru, M.D.; Shanenko, A.A.; Kaun, C.C.; Peeters, F.M. |
| Title |
Ultra-small metallic grains : effect of statistical fluctuations of the chemical potential on superconducting correlations and vice versa |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Journal of physics : condensed matter |
Abbreviated Journal |
J Phys-Condens Mat |
| Volume |
24 |
Issue |
27 |
Pages |
275701 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
Superconducting correlations in an isolated metallic grain are governed by the interplay between two energy scales: the mean level spacing delta and the bulk pairing gap Delta(0), which are strongly influenced by the position of the chemical potential with respect to the closest single-electron level. In turn superconducting correlations affect the position of the chemical potential. Within the parity projected BCS model we investigate the probability distribution of the chemical potential in a superconducting grain with randomly distributed single-electron levels. Taking into account statistical fluctuations of the chemical potential due to the pairing interaction, we find that such fluctuations have a significant impact on the critical level spacing delta(c) at which the superconducting correlations cease: the critical ratio delta(c)/Delta(0) at which superconductivity disappears is found to be increased. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
London |
Editor |
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| Language |
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Wos |
000305653100012 |
Publication Date |
2012-06-21 |
| Series Editor |
|
Series Title |
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Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0953-8984;1361-648X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.649 |
Times cited |
9 |
Open Access |
|
| Notes |
; This work was supported by the European Community under the Marie Curie IEF Action (Grant Agreement No. PIEF-GA-2009-235486-ScQSR), the Flemish Science Foundation (FWO-Vl), the Belgian Science Policy (IAP), and the ESF network INSTANS. MDC and AAS are grateful to A Vagov for stimulating discussions. ; |
Approved |
Most recent IF: 2.649; 2012 IF: 2.355 |
| Call Number |
UA @ lucian @ c:irua:100280 |
Serial |
3793 |
| Permanent link to this record |
| |
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| |
| Author |
Pina, J.C.; de Souza Silva, C.C.; Milošević, M.V. |
| Title |
Stability of fractional vortex states in a two-band mesoscopic superconductor |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
86 |
Issue |
2 |
Pages |
024512 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
We investigate the stability of noncomposite fractional vortex states in a mesoscopic two-band superconductor within the two-component Ginzburg-Landau model. Our analysis explicitly takes into account the relationship between the model parameters and microscopic material parameters, such as partial density of states, Fermi velocities and elements of the electron-phonon coupling matrix. We have found that states with different phase winding number in each band (L-1 not equal L-2) and fractional flux can exist in many different configurations, including rather unconventional ones where the dominating band carries larger winding number and states where vertical bar L-1 – L-2 vertical bar > 1. We present a detailed analysis of the stability of the observed vortex structures with respect to changing the microscopic parameters, showing that, in the weak coupling case, fractional vortex states can be assessed in essentially the whole range of temperatures and applied magnetic fields in which both bands are active. Finally, we propose an efficient way of increasing the range of parameters for which these fractional vortex states can be stabilized. In particular, our proposal allows for observation of fractional vortex structures in materials with stronger coupling, where those states are forbidden at a homogeneous field. This is accomplished with the help of the stray fields of a suitably prepared magnetic dot placed nearby the superconducting disk. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
Lancaster, Pa |
Editor |
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| Language |
|
Wos |
000306309600006 |
Publication Date |
2012-07-14 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
38 |
Open Access |
|
| Notes |
; We thank Eric B. Claude, Miguel A. Zorro, and Rogerio M. da Silva for assistance in the development of the numerical code used in our simulations. This work was supported by the Brazilian science agencies CNPq and FACEPE, by the FACEPE/CNPq-PRONEX program, under Grant No. APQ-0589-1.05/08, and by CNPq-FWO Brazil-Flanders co-operation program. M.V.M. acknowledges support from the CAPES-PVE program. ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:100766 |
Serial |
3126 |
| Permanent link to this record |
| |
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| |
| Author |
Neek-Amal, M.; Covaci, L.; Peeters, F.M. |
| Title |
Nanoengineered nonuniform strain in graphene using nanopillars |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
86 |
Issue |
4 |
Pages |
041405 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
Recent experiments showed that nonuniform strain can be produced by depositing graphene over pillars. We employed atomistic calculations to study the nonuniform strain and the induced pseudomagnetic field in graphene on top of nanopillars. By decreasing the distance between the nanopillars a complex distribution for the pseudomagnetic field can be generated. Furthermore, we performed tight-binding calculations of the local density of states (LDOS) by using the relaxed graphene configuration obtained from atomistic calculations. We find that the quasiparticle LDOS are strongly modified near the pillars, both at low energies showing sublattice polarization and at high energies showing shifts of the van Hove singularity. Our study shows that changing the specific pattern of the nanopillars allows us to create a desired shape of the pseudomagnetic field profile while the LDOS maps provide an input for experimental verification by scanning tunneling microscopy. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
Lancaster, Pa |
Editor |
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| Language |
|
Wos |
000306313900001 |
Publication Date |
2012-07-14 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
51 |
Open Access |
|
| Notes |
; This work was supported by the Flemish Science Foundation (FWO-V1) and the EuroGRAPHENE project CONGRAN. ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:100765 |
Serial |
2255 |
| Permanent link to this record |
| |
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| |
| Author |
Costamagna, S.; Neek-Amal, M.; Los, J.H.; Peeters, F.M. |
| Title |
Thermal rippling behavior of graphane |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
86 |
Issue |
4 |
Pages |
041408-4 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
Thermal fluctuations of single layer hydrogenated graphene (graphane) are investigated using large scale atomistic simulations. By analyzing the mean square value of the height fluctuations < h(2)> and the height-height correlation function H(q) for different system sizes and temperatures, we show that hydrogenated graphene is an unrippled system in contrast to graphene. The height fluctuations are bounded, which is confirmed by a H(q) tending to a constant in the long wavelength limit instead of showing the characteristic scaling law q(4-eta)(eta similar or equal to 0.85) predicted by membrane theory. This unexpected behavior persists up to temperatures of at least 900 K and is a consequence of the fact that in graphane the thermal energy can be accommodated by in-plane bending modes, i.e., modes involving C-C-C bond angles in the buckled carbon layer, instead of leading to significant out-of-plane fluctuations that occur in graphene. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
Lancaster, Pa |
Editor |
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| Language |
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Wos |
000306649200002 |
Publication Date |
2012-07-23 |
| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
46 |
Open Access |
|
| Notes |
; We thank A. Fasolino, A. Dobry, and K. H. Michel for their useful comments. S.C. is supported by the Belgian Science Foundation (BELSPO). This work is supported by the ESF-EuroGRAPHENE project CONGRAN and the Flemish Science Foundation (FWO-Vl). ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:100840 |
Serial |
3630 |
| Permanent link to this record |
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| Author |
Bousige, C.; Rols, S.; Paineau, E.; Rouziere, S.; Mocuta, C.; Verberck, B.; Wright, J.P.; Kataura, H.; Launois, P. |
| Title |
Progressive melting in confined one-dimensional C60 chains |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
86 |
Issue |
4 |
Pages |
045446 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
C-60 fullerenes confined inside single-walled carbon nanotubes form an archetypal one-dimensional system. X-ray diffraction experiments, from room temperature to 1073 K, reveal an increasing melting phenomenon. Detailed analysis of the sawtooth peak characteristic of the fullerene organization allows the quantitative determination of fluctuations in intermolecular distances. The present results validate the predictions of one-dimensional statistical models. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
Lancaster, Pa |
Editor |
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| Language |
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Wos |
000306925300007 |
Publication Date |
2012-08-01 |
| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
|
Open Access |
|
| Notes |
; ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:100835 |
Serial |
2726 |
| Permanent link to this record |
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| |
| Author |
Sena, S.H.R.; Pereira, J.M.; Farias, G.A.; Peeters, F.M. |
| Title |
Cyclotron resonance of trilayer graphene |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
86 |
Issue |
8 |
Pages |
085412 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
The cyclotron resonance energies, the corresponding oscillator strengths, and the cyclotron absorption spectrum for trilayer graphene are calculated for both ABA and ABC stacking. A gate potential across the stacked layers leads to (1) a reduction of the transition energies, (2) a lifting of the degeneracy of the zero Landau level, and (3) the removal of the electron-hole symmetry. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
Lancaster, Pa |
Editor |
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| Language |
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Wos |
000307273100009 |
Publication Date |
2012-08-08 |
| Series Editor |
|
Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
1098-0121;1550-235X; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
7 |
Open Access |
|
| Notes |
; This work was supported by the National Council for the Improvement of Higher education (CAPES), the Brazilian Council for Research (CNPq), the Flemish Science Foundation (FWO-V1), the bilateral projects between Flanders and Brazil and the CNPq and FWO-V1, and the ESF-Eurographene project CONGRAN. ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:100815 |
Serial |
604 |
| Permanent link to this record |
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| Author |
Zarenia, M.; Leenaerts, O.; Partoens, B.; Peeters, F.M. |
| Title |
Substrate-induced chiral states in graphene |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review : B : condensed matter and materials physics |
Abbreviated Journal |
Phys Rev B |
| Volume |
86 |
Issue |
8 |
Pages |
085451 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
Unidirectional chiral states are predicted in single layer graphene which originate from the breaking of the sublattice symmetry due to an asymmetric mass potential. The latter can be created experimentally using boron-nitride (BN) substrates with a line defect (B-B or N-N) that changes the induced mass potential in graphene. Solving the Dirac-Weyl equation, the obtained energy spectrum is compared with the one calculated using ab initio density functional calculations. We found that these one-dimensional chiral states are very robust and they can even exist in the presence of a small gap between the mass regions. In the latter case additional bound states are found that are topologically different from those chiral states. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
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Editor |
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| Language |
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Wos |
000308005600015 |
Publication Date |
2012-08-28 |
| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
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| ISSN |
1098-0121;1550-235X; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
41 |
Open Access |
|
| Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vl), and the European Science Foundation (ESF) under the EUROCORES Program: EuroGRAPHENE (project CONGRAN). ; |
Approved |
Most recent IF: 3.836; 2012 IF: 3.767 |
| Call Number |
UA @ lucian @ c:irua:101100 |
Serial |
3347 |
| Permanent link to this record |
