| Records |
| Author |
Stosic, D.; Mulkers, J.; Van Waeyenberge, B.; Ludermir, T.B.; Milošević, M.V. |
| Title |
Paths to collapse for isolated skyrmions in few-monolayer ferromagnetic films |
Type |
A1 Journal article |
| Year |
2017 |
Publication |
Physical review B |
Abbreviated Journal |
Phys Rev B |
| Volume |
95 |
Issue |
21 |
Pages |
214418 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
Magnetic skyrmions are topological spin configurations in materials with chiral Dzyaloshinskii-Moriya interaction (DMI), that are potentially useful for storing or processing information. To date, DMI has been found in few bulk materials, but can also be induced in atomically thin magnetic films in contact with surfaces with large spin-orbit interactions. Recent experiments have reported that isolated magnetic skyrmions can be stabilized even near room temperature in few-atom-thick magnetic layers sandwiched between materials that provide asymmetric spin-orbit coupling. Here we present the minimum-energy path analysis of three distinct mechanisms for the skyrmion collapse, based on ab initio input and the performed atomic-spin simulations. We focus on the stability of a skyrmion in three atomic layers of Co, either epitaxial on the Pt(111) surface or within a hybrid multilayer where DMI nontrivially varies per monolayer due to competition between different symmetry breaking from two sides of the Co film. In laterally finite systems, their constrained geometry causes poor thermal stability of the skyrmion toward collapse at the boundary, which we show to be resolved by designing the high-DMI structure within an extended film with lower or no DMI. |
| 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 |
000404015500001 |
Publication Date |
2017-06-23 |
| Series Editor |
|
Series Title |
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Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
2469-9950 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
48 |
Open Access |
|
| Notes |
This work was supported by the Research Foundation, Flanders (FWO-Vlaanderen) and Brazilian agency CNPq (Grants No. 442668/2014-7 and No. 140840/2016-8). |
Approved |
Most recent IF: 3.836 |
Call Number  |
CMT @ cmt @c:irua:144865 |
Serial |
4704 |
| Permanent link to this record |
| |
|
| |
| Author |
Chirayath, V.A.; Callewaert, V.; Fairchild, A.J.; Chrysler, M.D.; Gladen, R.W.; Mcdonald, A.D.; Imam, S.K.; Shastry, K.; Koymen, A.R.; Saniz, R.; Barbiellini, B.; Rajeshwar, K.; Partoens, B.; Weiss, A.H. |
| Title |
Auger electron emission initiated by the creation of valence-band holes in graphene by positron annihilation |
Type |
A1 Journal article |
| Year |
2017 |
Publication |
Nature communications |
Abbreviated Journal |
Nat Commun |
| Volume |
8 |
Issue |
8 |
Pages |
16116 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
| Abstract |
Auger processes involving the filling of holes in the valence band are thought to make important contributions to the low-energy photoelectron and secondary electron spectrum from many solids. However, measurements of the energy spectrum and the efficiency with which electrons are emitted in this process remain elusive due to a large unrelated background resulting from primary beam-induced secondary electrons. Here, we report the direct measurement of the energy spectra of electrons emitted from single layer graphene as a result of the decay of deep holes in the valence band. These measurements were made possible by eliminating competing backgrounds by employing low-energy positrons (<1.25 eV) to create valence-band holes by annihilation. Our experimental results, supported by theoretical calculations, indicate that between 80 and 100% of the deep valence-band holes in graphene are filled via an Auger transition. |
| 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 |
000405398200001 |
Publication Date |
2017-07-13 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
2041-1723 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
12.124 |
Times cited |
20 |
Open Access |
|
| Notes |
The experiments in this work were supported by the grant NSF DMR 1508719. A.H.W and A.R.K. gratefully acknowledge support for the building of advanced positron beam through the grant NSF DMR MRI 1338130. V.C. and R.S. were supported by the FWO-Vlaanderen through Project No. G. 0224.14N. The computational resources and services used in this work were in part provided by the VSC (Flemish Supercomputer Center) and the HPC infrastructure of the University of Antwerp (CalcUA), both funded by the Hercules Foundation and the Flemish Government (EWI Department). The work at Northeastern University was supported by the US Department of Energy (DOE), Office of Science, Basic Energy Sciences grant number DE-FG02-07ER46352 (core research), and benefited from Northeastern University’s Advanced Scientific Computation Center (ASCC), the NERSC supercomputing center through DOE grant number DE-AC02-05CH11231, and support (applications to layered materials) from the DOE EFRC: Center for the Computational Design of Functional Layered Materials (CCDM) under DE-SC0012575. |
Approved |
Most recent IF: 12.124 |
| Call Number |
CMT @ cmt @ c:irua:144625 |
Serial |
4627 |
| Permanent link to this record |
| |
|
| |
| Author |
Ghorbanfekr-Kalashami, H.; Vasu, K.S.; Nair, R.R.; Peeters, F.M.; Neek-Amal, M. |
| Title |
Dependence of the shape of graphene nanobubbles on trapped substance |
Type |
A1 Journal article |
| Year |
2017 |
Publication |
Nature communications |
Abbreviated Journal |
Nat Commun |
| Volume |
8 |
Issue |
8 |
Pages |
15844 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
| Abstract |
Van der Waals (vdW) interaction between two-dimensional crystals (2D) can trap substances in high pressurized (of order 1 GPa) on nanobubbles. Increasing the adhesion between the 2D crystals further enhances the pressure and can lead to a phase transition of the trapped material. We found that the shape of the nanobubble can depend critically on the properties of the trapped substance. In the absence of any residual strain in the top 2D crystal, flat nanobubbles can be formed by trapped long hydrocarbons (that is, hexadecane). For large nanobubbles with radius 130 nm, our atomic force microscopy measurements show nanobubbles filled with hydrocarbons (water) have a cylindrical symmetry (asymmetric) shape which is in good agreement with our molecular dynamics simulations. This study provides insights into the effects of the specific material and the vdW pressure on the microscopic details of graphene bubbles. |
| 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 |
000403417500001 |
Publication Date |
2017-06-16 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
2041-1723 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
12.124 |
Times cited |
44 |
Open Access |
|
| Notes |
We acknowledge fruitful discussion with Irina Grigorieva and Andre K. Geim. This work was supported by the Flemish Science Foundation (FWO-Vl) and the Methusalem program, the Royal Society and the Engineering and Physical Sciences Research Council, UK (EP/K016946/1). M.N.-A. was supported by Iran National Science Foundation (INSF). |
Approved |
Most recent IF: 12.124 |
| Call Number |
CMT @ cmt @ c:irua:144189 |
Serial |
4580 |
| Permanent link to this record |
| |
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| |
| Author |
Han, F.W.; Xu, W.; Li, L.L.; Zhang, C.; Dong, H.M.; Peeters, F.M. |
| Title |
Electronic and transport properties of n-type monolayer black phosphorus at low temperatures |
Type |
A1 Journal article |
| Year |
2017 |
Publication |
Physical review B |
Abbreviated Journal |
Phys Rev B |
| Volume |
95 |
Issue |
95 |
Pages |
115436 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
We present a detailed theoretical study of the electronic and transport properties of monolayer black phosphorus (BP). This study is motivated by recent experimental activities in investigating n-type few-layer BP systems. The electron density of states, the screening length, and the low-temperature electron mobility are calculated for monolayer BP (MLBP). In particular, the electron transport mobilities along the armchair and zigzag directions are examined on the basis of the momentum-balance equation derived from a semiclassical Boltzmann equation. The anisotropic electron mobilities in MLBP along different directions are demonstrated where the electron-impurity scattering is considered. Furthermore, we compare the results obtained from two electronic band structures of MLBP and find that the simplified model can describe quite rightly the electronic and transport properties of MLBP. This study is relevant to the application of few-layer BP based electronic systems as advanced electronic devices. |
| 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 |
000399140700012 |
Publication Date |
2017-03-27 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
2469-9950 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
12 |
Open Access |
|
| Notes |
National Natural Science Foundation of China, 11574319 11304316 11304317 11604380 ; Ministry of Science and Technology of the People's Republic of China, 2011YQ130018 ; Chinese Academy of Sciences; |
Approved |
Most recent IF: 3.836 |
| Call Number |
CMT @ cmt @ c:irua:142431 |
Serial |
4564 |
| Permanent link to this record |
| |
|
| |
| Author |
Mulkers, J.; Van Waeyenberge, B.; Milošević, M.V. |
| Title |
Effects of spatially engineered Dzyaloshinskii-Moriya interaction in ferromagnetic films |
Type |
A1 Journal article |
| Year |
2017 |
Publication |
Physical review B |
Abbreviated Journal |
Phys Rev B |
| Volume |
95 |
Issue |
95 |
Pages |
144401 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
The Dzyaloshinskii-Moriya interaction (DMI) is a chiral interaction that favors formation of domain walls. Recent experiments and ab initio calculations show that there are multiple ways to modify the strength of the interfacially induced DMI in thin ferromagnetic films with perpendicular magnetic anisotropy. In this paper we reveal theoretically the effects of spatially varied DMI on the magnetic state in thin films. In such heterochiral 2D structures we report several emergent phenomena, ranging from the equilibrium spin canting at the interface between regions with different DMI, over particularly strong confinement of domain walls and skyrmions within high-DMI tracks, to advanced applications such as domain tailoring nearly at will, design of magnonic waveguides, and much improved skyrmion racetrack memory. |
| 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 |
000399382100003 |
Publication Date |
2017-04-03 |
| Series Editor |
|
Series Title |
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Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
2469-9950 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.836 |
Times cited |
60 |
Open Access |
|
| Notes |
Fonds Wetenschappelijk Onderzoek, G098917N ; |
Approved |
Most recent IF: 3.836 |
| Call Number |
CMT @ cmt @ c:irua:141917 |
Serial |
4534 |
| Permanent link to this record |
| |
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| |
| Author |
Eijt, S.W.H.; Shi, W.; Mannheim, A.; Butterling, M.; Schut, H.; Egger, W.; Dickmann, M.; Hugenschmidt, C.; Shakeri, B.; Meulenberg, R.W.; Callewaert, V.; Saniz, R.; Partoens, B.; Barbiellini, B.; Bansil, A.; Melskens, J.; Zeman, M.; Smets, A.H.M.; Kulbak, M.; Hodes, G.; Cahen, D.; Brück, E. |
| Title |
New insights into the nanostructure of innovative thin film solar cells gained by positron annihilation spectroscopy |
Type |
A1 Journal article |
| Year |
2017 |
Publication |
Journal of physics : conference series |
Abbreviated Journal |
|
| Volume |
791 |
Issue |
791 |
Pages |
012021 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
Recent studies showed that positron annihilation methods can provide key insights into the nanostructure and electronic structure of thin film solar cells. In this study, positron annihilation lifetime spectroscopy (PALS) is applied to investigate CdSe quantum dot (QD) light absorbing layers, providing evidence of positron trapping at the surfaces of the QDs. This enables one to monitor their surface composition and electronic structure. Further, 2D-Angular Correlation of Annihilation Radiation (2D-ACAR) is used to investigate the nanostructure of divacancies in photovoltaic-high-quality a-Si:H films. The collected momentum distributions were converted by Fourier transformation to the direct space representation of the electron-positron autocorrelation function. The evolution of the size of the divacancies as a function of hydrogen dilution during deposition of a-Si:H thin films was examined. Finally, we present a first positron Doppler Broadening of Annihilation Radiation (DBAR) study of the emerging class of highly efficient thin film solar cells based on perovskites. |
| 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 |
000400610500021 |
Publication Date |
2017-02-22 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1742-6588 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
|
Times cited |
1 |
Open Access |
|
| Notes |
The work at Delft University of Technology was supported by the China Scholarship Council (CSC) grant of W.S., by ADEM, A green Deal in Energy Materials of the Ministry of Economic Affairs of The Netherlands (www.adem- innovationlab.nl), and the STW Vidi grant of A.S., Grant No. 10782. The PALS study is based upon experiments performed at the PLEPS instrument of the NEPOMUC facility at the Heinz Maier-Leibnitz Zentrum (MLZ), Garching, Germany, and was supported by the European Commission under the 7 th Framework Programme, Key Action: Strengthening the European Research Area, Research Infrastructures, Contract No. 226507, NMI3. The work at University of Maine was supported by the National Science Foundation under Grant No. DMR-1206940. Research at the University of Antwerp was supported by FWO grants G022414N and G015013. The work at Northeastern University was supported by the US Department of Energy (DOE), Office of Science, Basic Energy Sciences grant number DE-FG02-07ER46352 (core research), and benefited from Northeastern University's Advanced Scientific Computation Center (ASCC), the NERSC supercomputing center through DOE grant number DE-AC02-05CH11231, and support (applications to layered materials) from the DOE EFRC: Center for the Computational Design of Functional Layered Materials (CCDM) under DE-SC0012575. The work at the Weizmann Institute was supported by the Sidney E. Frank Foundation through the Israel Science Foundation, by the Israel Ministry of Science, and the Israel National Nano-Initiative. D.C. holds the Sylvia and Rowland Schaefer Chair in Energy Research. |
Approved |
Most recent IF: NA |
| Call Number |
CMT @ cmt @ c:irua:140850 |
Serial |
4426 |
| Permanent link to this record |
| |
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| |
| Author |
Callewaert, V.; Saniz, R.; Barbiellini, B.; Partoens, B. |
| Title |
Surface states and positron annihilation spectroscopy: results and prospects from a first-principles approach |
Type |
A1 Journal article |
| Year |
2017 |
Publication |
Journal of physics : conference series |
Abbreviated Journal |
|
| Volume |
791 |
Issue |
791 |
Pages |
012036 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
The trapping of positrons at the surface of a material can be exploited to study quite selectively the surface properties of the latter by means of positron annihilation spectroscopy techniques. To support these, it is desirable to be able to theoretically predict the existence of such positronic surface states and to describe their annihilation characteristics with core or valence surface electrons in a reliable way. Here, we build on the well-developed first-principles techniques for the study of positrons in bulk solids as well as on previous models for surfaces, and investigate two schemes that can improve the theoretical description of the interaction of positrons with surfaces. One is based on supplementing the local-density correlation potential with the corrugated image potential at the surface, and the other is based on the weighted-density approximation to correlation. We discuss our results for topological insulators, graphene layers, and quantum dots, with emphasis on the information that can be directly related to experiment. We also discuss some open theoretical problems that should be addressed by future research. |
| 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 |
000400610500036 |
Publication Date |
2017-02-22 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1742-6588 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
|
Times cited |
1 |
Open Access |
|
| Notes |
We acknowledge financial support from FWO-Vlaanderen (projects G.0150.13 and G.0224.14N). This work was carried out using the HPC infrastructure of the University of Antwerp (CalcUA), a division of the Flemish Supercomputer Center (VSC), funded by the Hercules foundation and the Flemish Government (EWI Department). The work at Northeastern University was supported by the US Department of Energy (DOE), Office of Science, Basic Energy Sciences grant number DE-FG02-07ER46352 (core research), and benefited from Northeastern University’s Advanced Scientific Computation Center (ASCC), the NERSC supercomputing center through DOE grant number DE-AC02- 05CH11231, and support (applications to layered materials) from the DOE EFRC: Center for the Computational Design of Functional Layered Materials (CCDM) under DE-SC0012575. |
Approved |
Most recent IF: NA |
| Call Number |
CMT @ cmt @ c:irua:140847 |
Serial |
4425 |
| Permanent link to this record |
| |
|
| |
| Author |
Asapu, R.; Claes, N.; Bals, S.; Denys, S.; Detavernier, C.; Lenaerts, S.; Verbruggen, S.W. |
| Title |
Silver-polymer core-shell nanoparticles for ultrastable plasmon-enhanced photocatalysis |
Type |
A1 Journal article |
| Year |
2017 |
Publication |
Applied catalysis : B : environmental |
Abbreviated Journal |
Appl Catal B-Environ |
| Volume |
200 |
Issue |
200 |
Pages |
31-38 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Sustainable Energy, Air and Water Technology (DuEL) |
| Abstract |
Affordable silver-polymer core-shell nanoparticles are prepared using the layer-by-layer (LbL) technique. The metallic silver core is encapsulated with an ultra-thin protective shell that prevents oxidation and clustering without compromising the plasmonic properties. The core-shell nanoparticles retain their plasmonic near field enhancement effect, as studied from finite element numerical simulations. Control over the shell thickness up to the sub-nanometer level is there for key. The particles are used to prepare a plasmonic Ag-TiO2 photocatalyst of which the gas phase photocatalytic activity is monitored over a period of four months. The described system outperforms pristine TiO2 and retains its plasmonic enhancement in contrast to TiO2 modified with bare silver nanoparticles. With this an important step is made toward the development of long-term stable plasmonic (photocatalytic) applications. |
| 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 |
000384775600004 |
Publication Date |
2016-06-28 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0926-3373 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
9.446 |
Times cited |
45 |
Open Access |
OpenAccess |
| Notes |
CD, SL and SWV acknowledge the Research Foundation − Flanders (FWO) for financial support. CD further acknowledges BOF-UGent (GOA 01G01513) and the Hercules Foundation (AUGE/09/014). SB acknowledges the European Research Council for the ERC Starting Grant #335078-COLOURATOM.; ECAS_Sara; (ROMEO:green; preprint:; postprint:can ; pdfversion:cannot); |
Approved |
Most recent IF: 9.446 |
| Call Number |
c:irua:134384 c:irua:134384UA @ admin @ c:irua:134384 |
Serial |
4104 |
| Permanent link to this record |
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| |
| Author |
Béché, A.; Juchtmans, R.; Verbeeck, J. |
| Title |
Efficient creation of electron vortex beams for high resolution STEM imaging |
Type |
A1 Journal article |
| Year |
2017 |
Publication |
Ultramicroscopy |
Abbreviated Journal |
Ultramicroscopy |
| Volume |
178 |
Issue |
178 |
Pages |
12-19 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT) |
| Abstract |
The recent discovery of electron vortex beams carrying quantised angular momentum in the TEM has led to an active field of research, exploring a variety of potential applications including the possibility of mapping magnetic states at the atomic scale. A prerequisite for this is the availability of atomic sized electron vortex beams at high beam current and mode purity. In this paper we present recent progress showing that by making use of the Aharonov-Bohm effect near the tip of a long single domain ferromagnetic Nickel needle, a very efficient aperture for the production of electron vortex beams can be realised. The aperture transmits more than 99% of all electrons and provides a vortex mode purity of up to 92%. Placing this aperture in the condenser plane of a state of the art Cs corrected microscope allows us to demonstrate atomic resolution HAADF STEM images with spatial resolution better than 1 Angstrom, in agreement with theoretical expectations and only slightly inferior to the performance of a non-vortex probe on the same instrument. |
| Address |
EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium |
| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
|
Editor |
|
| Language |
English |
Wos |
000403862900003 |
Publication Date |
2016-05-10 |
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0304-3991 |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
2.843 |
Times cited |
30 |
Open Access |
OpenAccess |
| Notes |
A.B. and J.V. acknowledge funding from the European Research Council under the 7th Framework Program (FP7), ERC Starting Grant No. 278510 VORTEX. J.V. acknowledges funding from FWO project G.0044.13N ('Charge ordering').; ECASJO_; |
Approved |
Most recent IF: 2.843 |
| Call Number |
c:irua:134085 c:irua:134085UA @ admin @ c:irua:134085 |
Serial |
4094 |
| Permanent link to this record |
