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Author |
Callewaert, V.; Shastry, K.; Saniz, R.; Makkonen, I.; Barbiellini, B.; Assaf, B.A.; Heiman, D.; Moodera, J.S.; Partoens, B.; Bansil, A.; Weiss, A.H.; |
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Title |
Positron surface state as a spectroscopic probe for characterizing surfaces of topological insulator materials |
Type |
A1 Journal article |
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Year |
2016 |
Publication |
Physical review B |
Abbreviated Journal |
Phys Rev B |
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Volume |
94 |
Issue |
94 |
Pages |
115411 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Topological insulators are attracting considerable interest due to their potential for technological applications and as platforms for exploring wide-ranging fundamental science questions. In order to exploit, fine-tune, control, and manipulate the topological surface states, spectroscopic tools which can effectively probe their properties are of key importance. Here, we demonstrate that positrons provide a sensitive probe for topological states and that the associated annihilation spectrum provides a technique for characterizing these states. Firm experimental evidence for the existence of a positron surface state near Bi2Te2Se with a binding energy of E-b = 2.7 +/- 0.2 eV is presented and is confirmed by first-principles calculations. Additionally, the simulations predict a significant signal originating from annihilation with the topological surface states and show the feasibility to detect their spin texture through the use of spin-polarized positron beams. |
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Wos |
000383232800012 |
Publication Date |
2016-09-06 |
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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 |
2469-9950;2469-9969; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
15 |
Open Access |
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Notes |
; I.M. acknowledges discussions with M. Ervasti and A. Harju. 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 paper 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). I.M. acknowledges financial support from the Academy of Finland (Projects No. 285809 and No. 293932). The work at Northeastern University was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences Grant No. DE-FG02-07ER46352 and benefited from Northeastern University's Advanced Scientific Computation Center (ASCC) and the NERSC supercomputing center through DOE Grant No. DE-AC02-05CH11231. K.S. and A.W. acknowledge financial support from the National Science Foundation through Grants No. DMR-MRI-1338130 and No. DMR-1508719. D.H. received financial support from the National Science Foundation (Grant No. ECCS-1402738). J.S.M. was supported by the STC Center for Integrated Quantum Materials under NSF Grants No. DMR-1231319, No. DMR-1207469, and ONR Grant No. N00014-13-1-0301. B.A.A. also acknowledges support from the LabEx ENS-ICFP Grant No. ANR-10-LABX-0010/ANR-10-IDEX-0001-02 PSL. ; |
Approved |
Most recent IF: 3.836 |
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Call Number |
UA @ lucian @ c:irua:137134 |
Serial |
4362 |
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Permanent link to this record |
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Author |
Callewaert, V.; Saniz, R.; Barbiellini, B.; Bansil, A.; Partoens, B. |
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Title |
Application of the weighted-density approximation to the accurate description of electron-positron correlation effects in materials |
Type |
A1 Journal article |
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Year |
2017 |
Publication |
Physical review B |
Abbreviated Journal |
Phys Rev B |
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Volume |
96 |
Issue |
8 |
Pages |
085135 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
We discuss positron-annihilation lifetimes for a set of illustrative bulk materials within the framework of the weighted-density approximation (WDA). The WDA can correctly describe electron-positron correlations in strongly inhomogeneous systems, such as surfaces, where the applicability of (semi-)local approximations is limited. We analyze the WDA in detail and show that the electrons which cannot screen external charges efficiently, such as the core electrons, cannot be treated accurately via the pair correlation of the homogeneous electron gas. We discuss how this problem can be addressed by reducing the screening in the homogeneous electron gas by adding terms depending on the gradient of the electron density. Further improvements are obtained when core electrons are treated within the LDA and the valence electron using the WDA. Finally, we discuss a semiempirical WDA-based approach in which a sum rule is imposed to reproduce the experimental lifetimes. |
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Wos |
000408342600003 |
Publication Date |
2017-08-24 |
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Edition |
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ISSN |
2469-9950 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.836 |
Times cited |
6 |
Open Access |
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Notes |
Fonds Wetenschappelijk Onderzoek, G. 0224.14N ; U.S. Department of Energy, DE-FG02-07ER46352 DE-AC02-05CH11231 DE-SC0012575 ; |
Approved |
Most recent IF: 3.836 |
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Call Number |
CMT @ cmt @c:irua:145703 |
Serial |
4703 |
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Permanent link to this record |
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Author |
Saniz, R.; Dixit, H.; Lamoen, D.; Partoens, B. |
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Title |
Quasiparticle energies and uniaxial pressure effects on the properties of SnO2 |
Type |
A1 Journal article |
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Year |
2010 |
Publication |
Applied physics letters |
Abbreviated Journal |
Appl Phys Lett |
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Volume |
97 |
Issue |
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Pages |
261901-261901,3 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
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Abstract |
We calculate the quasiparticle energy spectrum of SnO2 within the GW approximation, properly taking into account the contribution of core levels to the energy corrections. The calculated fundamental gap is of 3.85 eV. We propose that the difference with respect to the experimental optical gap (3.6 eV) is due to excitonic effects in the latter. We further consider the effect applied on uniaxial pressure along the c-axis. Compared to GW, the effect of pressure on the quasiparticle energies and band gap is underestimated by the local-density approximation. The quasiparticle effective masses, however, appear to be well described by the latter. |
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Publisher |
American Institute of Physics |
Place of Publication |
New York, N.Y. |
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Wos |
000285768100015 |
Publication Date |
2010-12-28 |
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Series Volume |
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Edition |
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ISSN |
0003-6951; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.411 |
Times cited |
23 |
Open Access |
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Notes |
Iwt; Fwo; Bof-Noi |
Approved |
Most recent IF: 3.411; 2010 IF: 3.841 |
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Call Number |
UA @ lucian @ c:irua:85759 |
Serial |
2803 |
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Permanent link to this record |
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Author |
Saniz, R.; Norman, M.R.; Freeman, A.J. |
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Title |
Orbital mixing and nesting in the bilayer manganites La2-2xSr1+2xMn2O7 |
Type |
A1 Journal article |
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Year |
2008 |
Publication |
Physical review letters |
Abbreviated Journal |
Phys Rev Lett |
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Volume |
101 |
Issue |
23 |
Pages |
236402-236404 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
A first principles study of La(2-2x)Sr(1+2x)Mn(2)O(7) compounds for doping levels 0.3 <= x <= 0.5 shows that the low energy electronic structure of the majority spin carriers is determined by strong momentum-dependent interactions between the Mn e(g) d(x)(2)-y(2) and d(3z)(2)-r(2) orbitals, which, in addition to an x-dependent Jahn-Teller distortion, differ in the ferromagnetic and antiferromagnetic phases. The Fermi surface exhibits nesting behavior that is reflected by peaks in the static susceptibility, whose positions as a function of momentum have a nontrivial dependence on x. |
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Place of Publication |
New York, N.Y. |
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Wos |
000261431200045 |
Publication Date |
2008-12-03 |
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Series Issue |
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Edition |
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ISSN |
0031-9007;1079-7114; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
8.462 |
Times cited |
14 |
Open Access |
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Notes |
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Approved |
Most recent IF: 8.462; 2008 IF: 7.180 |
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Call Number |
UA @ lucian @ c:irua:102602 |
Serial |
2498 |
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Author |
Amini, M.N.; Saniz, R.; Lamoen, D.; Partoens, B. |
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Title |
Hydrogen impurities and native defects in CdO |
Type |
A1 Journal article |
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Year |
2011 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
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Volume |
110 |
Issue |
6 |
Pages |
063521,1-063521,7 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
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Abstract |
We have used first-principles calculations based on density functional theory to study point defects in CdO within the local density approximation and beyond (LDA+U). Hydrogen interstitials and oxygen vacancies are found to act as shallow donors and can be interpreted as the cause of conductivity in CdO. Hydrogen can also occupy an oxygen vacancy in its substitutional form and also acts as a shallow donor. Similar to what was found for ZnO and MgO, hydrogen creates a multicenter bond with its six oxygen neighbors in CdO. The charge neutrality level for native defects and hydrogen impurities has been calculated. It is shown that in the case of native defects, it is not uniquely defined. Indeed, this level depends highly on the chemical potentials of the species and one can obtain different values for different end states in the experiment. Therefore, a comparison with experiment can only be made if the chemical potentials of the species in the experiment are well defined. However, for the hydrogen interstitial defect, since this level is independent of the chemical potential of hydrogen, one can obtain a unique value for the charge neutrality level. We find that the Fermi level stabilizes at 0.43 eV above the conduction band minimum in the case of the hydrogen interstitial defect, which is in good agreement with the experimentally reported value of 0.4 eV. |
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Publisher |
American Institute of Physics |
Place of Publication |
New York, N.Y. |
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Wos |
000295619300041 |
Publication Date |
2011-09-23 |
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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 |
0021-8979; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.068 |
Times cited |
13 |
Open Access |
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Notes |
; The authors gratefully acknowledge financial support from the IWT-Vlaanderen through the ISIMADE project, the FWO-Vlaanderen through Project G.0191.08 and the BOF-NOI of the University of Antwerp. This work was carried out using the HPC infrastructure at the University of Antwerp (CalcUA), a division of the Flemish Supercomputer Center VSC. ; |
Approved |
Most recent IF: 2.068; 2011 IF: 2.168 |
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Call Number |
UA @ lucian @ c:irua:93613 |
Serial |
1533 |
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Author |
Sarmadian, N.; Saniz, R.; Partoens, B.; Lamoen, D. |
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Title |
Ab initio study of shallow acceptors in bixbyite V2O3 |
Type |
A1 Journal article |
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Year |
2015 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
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Volume |
117 |
Issue |
117 |
Pages |
015703 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
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Abstract |
We present the results of our study on p-type dopability of bixbyite V2O3 using the Heyd, Scuseria, and Ernzerhof hybrid functional (HSE06) within the density functional theory (DFT) formalism. We study vanadium and oxygen vacancies as intrinsic defects and substitutional Mg, Sc, and Y as extrinsic defects. We find that Mg substituting V acts as a shallow acceptor, and that oxygen vacancies are electrically neutral. Hence, we predict Mg-doped V2O3 to be a p-type conductor. Our results also show that vanadium vacancies are relatively shallow, with a binding energy of 0.14 eV, so that they might also lead to p-type conductivity. |
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Publisher |
American Institute of Physics |
Place of Publication |
New York, N.Y. |
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Wos |
000347958600067 |
Publication Date |
2015-01-05 |
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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 |
0021-8979;1089-7550; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.068 |
Times cited |
3 |
Open Access |
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Notes |
FWO G015013; Hercules |
Approved |
Most recent IF: 2.068; 2015 IF: 2.183 |
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Call Number |
c:irua:122728 |
Serial |
35 |
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Author |
Bekaert, J.; Saniz, R.; Partoens, B.; Lamoen, D. |
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Title |
First-principles study of carbon impurities in CuInSe2 and CuGaSe2, present in non-vacuum synthesis methods |
Type |
A1 Journal article |
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Year |
2015 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
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Volume |
117 |
Issue |
117 |
Pages |
015104 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
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Abstract |
A first-principles study of the structural and electronic properties of carbon impurities in CuInSe2 and CuGaSe2 is presented. Carbon is present in organic molecules in the precursor solutions used in non-vacuum growth methods for CuInSe2 and CuGaSe2 based photovoltaic cells. These growth methods make more efficient use of material, time, and energy than traditional vacuum methods. The formation energies of several carbon impurities are calculated using the hybrid HSE06 functional. C Cu acts as a shallow donor, CIn and interstitial C yield deep donor levels in CuInSe2, while in CuGaSe2 CGa and interstitial C act as deep amphoteric defects. So, these defects reduce the majority carrier (hole) concentration in p-type CuInSe2 and CuGaSe2 by compensating the acceptor levels. The deep defects are likely to act as recombination centers for the photogenerated charge carriers and are thus detrimental for the performance of the photovoltaic cells. On the other hand, the formation energies of the carbon impurities are high, even under C-rich growth conditions. Thus, few C impurities will form in CuInSe2 and CuGaSe2 in thermodynamic equilibrium. However, the deposition of the precursor solution in non-vacuum growth methods presents conditions far from thermodynamic equilibrium. In this case, our calculations show that C impurities formed in non-equilibrium tend to segregate from CuInSe2 and CuGaSe2 by approaching thermodynamic equilibrium, e.g., via thorough annealing. |
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Thesis |
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Publisher |
American Institute of Physics |
Place of Publication |
New York, N.Y. |
Editor |
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Language |
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Wos |
000347958600055 |
Publication Date |
2015-01-07 |
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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 |
0021-8979;1089-7550; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.068 |
Times cited |
6 |
Open Access |
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Notes |
FWO G015013; Hercules |
Approved |
Most recent IF: 2.068; 2015 IF: 2.183 |
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Call Number |
c:irua:122064 |
Serial |
1215 |
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Permanent link to this record |
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Author |
Sarmadian, N.; Saniz, R.; Partoens, B.; Lamoen, D. |
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Title |
First-principles study of the optoelectronic properties and photovoltaic absorber layer efficiency of Cu-based chalcogenides |
Type |
A1 Journal article |
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Year |
2016 |
Publication |
Journal of applied physics |
Abbreviated Journal |
J Appl Phys |
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Volume |
120 |
Issue |
120 |
Pages |
085707 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
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Abstract |
Cu-based chalcogenides are promising materials for thin-film solar cells with more than 20% measured
cell efficiency. Using first-principles calculations based on density functional theory, the
optoelectronic properties of a group of Cu-based chalcogenides Cu2-II-IV-VI4 is studied. They are
then screened with the aim of identifying potential absorber materials for photovoltaic applications.
The spectroscopic limited maximum efficiency (SLME) introduced by Yu and Zunger [Phys. Rev.
Lett. 108, 068701 (2012)] is used as a metric for the screening. After constructing the currentvoltage
curve, the SLME is calculated from the maximum power output. The role of the nature of
the band gap, direct or indirect, and also of the absorptivity of the studied materials on the maximum
theoretical power conversion efficiency is studied. Our results show that Cu2II-GeSe4 with
II¼ Cd and Hg, and Cu2-II-SnS4 with II ¼ Cd, Hg, and Zn have a higher theoretical efficiency
compared with the materials currently used as absorber layer. |
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Place of Publication |
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Wos |
000383913400074 |
Publication Date |
2016-08-30 |
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Series Editor |
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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 |
0021-8979 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.068 |
Times cited |
29 |
Open Access |
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Notes |
We acknowledge the financial support from the FWO-Vlaanderen through project G.0150.13N and a GOA fund from the University of Antwerp. The computational resources and services used in this work were provided by the VSC (Flemish Supercomputer Center) and the HPC infrastructure of the University of Antwerp (CalcUA), bothfunded by the FWO-Vlaanderen and the Flemish Government–department EWI. |
Approved |
Most recent IF: 2.068 |
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Call Number |
c:irua:135089 |
Serial |
4113 |
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Permanent link to this record |
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Author |
Shi, W.; Callewaert, V.; Barbiellini, B.; Saniz, R.; Butterling, M.; Egger, W.; Dickmann, M.; Hugenschmidt, C.; Shakeri, B.; Meulenberg, R. W.; Brück, E.; Partoens, B.; Bansil, A.; Eijt, S.W. H. |
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Title |
Nature of the Positron State in CdSe Quantum Dots |
Type |
A1 Journal article |
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Year |
2018 |
Publication |
Physical review letters |
Abbreviated Journal |
Phys Rev Lett |
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Volume |
121 |
Issue |
5 |
Pages |
057401 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
Previous studies have shown that positron-annihilation spectroscopy is a highly sensitive probe of the electronic structure and surface composition of ligand-capped semiconductor quantum dots (QDs) embedded in thin films. The nature of the associated positron state, however, whether the positron is confined inside the QDs or localized at their surfaces, has so far remained unresolved. Our positron-annihilation lifetime spectroscopy studies of CdSe QDs reveal the presence of a strong lifetime component in the narrow range of 358–371 ps, indicating abundant trapping and annihilation of positrons at the surfaces of the QDs. Furthermore, our ab initio calculations of the positron wave function and lifetime employing a recent formulation of the weighted density approximation demonstrate the presence of a positron surface state and predict positron lifetimes close to experimental values. Our study thus resolves the long-standing question regarding the nature of the positron state in semiconductor QDs and opens the way to extract quantitative information on surface composition and ligand-surface interactions of colloidal semiconductor QDs through highly sensitive positron-annihilation techniques. |
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Place of Publication |
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Wos |
000440635300012 |
Publication Date |
2018-08-02 |
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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 |
0031-9007 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
8.462 |
Times cited |
6 |
Open Access |
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Notes |
The work at Delft University of Technology was supported by the China Scholarship Council (CSC) grant of W. S. We acknowledge financial support for this research from ADEM, A green Deal in Energy Materials of the Ministry of Economic Affairs of The Netherlands. 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 7th Framework Program, Key Action: Strengthening the European Research Area, Research Infrastructures, Contract No. 226507, NMI3. The work at the University of Maine was supported by the National Science Foundation under Grant No. DMR-1206940. V. C. and R. S. were supported by the FWO-Vlaanderen through Project No. G. 0224.14N. 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 FWO-Vlaanderen and the Flemish Government (EWI Department). The work at Northeastern University was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences Grant No. DE-FG02-07ER46352 (core research), and benefited from Northeastern University’s Advanced Scientific Computation Center (ASCC), the National Energy Research Scientific Computing Center (NERSC) through DOE Grant No. DE-AC02-05CH11231, and support (functionals for modeling positron spectros- copies of layered materials) from the DOE EFRC: Center for the Computational Design of Functional Layered Materials (CCDM) under DE-SC0012575. |
Approved |
Most recent IF: 8.462 |
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Call Number |
CMT @ cmt @c:irua:152999UA @ admin @ c:irua:152999 |
Serial |
5009 |
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Permanent link to this record |
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Author |
De Beule, C.; Saniz, R.; Partoens, B. |
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Title |
Crystalline topological states at a topological insulator junction |
Type |
A1 Journal article |
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Year |
2019 |
Publication |
The journal of physics and chemistry of solids |
Abbreviated Journal |
J Phys Chem Solids |
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Volume |
128 |
Issue |
128 |
Pages |
144-151 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
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Abstract |
We consider an interface between two strong time-reversal invariant topological insulators having surface states with opposite spin chirality, or equivalently, opposite mirror Chern number. We show that such an interface supports gapless modes that are protected by mirror symmetry. The interface states are investigated with a continuum model for the Bi2Se3 class of topological insulators that takes into account terms up to third order in the crystal momentum, which ensures that the model has the correct symmetry. The model parameters are obtained from ab initio calculations. Finally, we consider the effect of rotational mismatch at the interface, which breaks the mirror symmetry and opens a gap in the interface spectrum. |
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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 |
000472693100013 |
Publication Date |
2018-01-31 |
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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 |
0022-3697 |
ISBN |
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Additional Links |
UA library record; WoS full record |
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Impact Factor |
2.059 |
Times cited |
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Open Access |
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Notes |
; ; |
Approved |
Most recent IF: 2.059 |
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Call Number |
UA @ admin @ c:irua:161391 |
Serial |
5385 |
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Permanent link to this record |
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Author |
Saniz, R.; Sarmadian, N.; Partoens, B.; Batuk, M.; Hadermann, J.; Marikutsa, A.; Rumyantseva, M.; Gaskov, A.; Lamoen, D. |
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Title |
First-principles study of CO and OH adsorption on in-doped ZnO surfaces |
Type |
A1 Journal article |
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Year |
2019 |
Publication |
The journal of physics and chemistry of solids |
Abbreviated Journal |
J Phys Chem Solids |
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Volume |
132 |
Issue |
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Pages |
172-181 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
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Abstract |
We present a first-principles computational study of CO and OH adsorption on non-polar ZnO (10¯10) surfaces doped with indium. The calculations were performed using a model ZnO slab. The position of the In dopants was varied from deep bulk-like layers to
the surface layers. It was established that the preferential location of the In atoms is at the surface by examining the dependence of
the defect formation energy as well as the surface energy on In location. The adsorption sites on the surface of ZnO and the energy
of adsorption of CO molecules and OH-species were determined in connection to In doping. It was found that OH has higher
bonding energy to the surface than CO. The presence of In atoms at the surface of ZnO is favorable for CO adsorption, resulting
in an elongation of the C-O bond and in charge transfer to the surface. The effect of CO and OH adsorption on the electronic
and conduction properties of surfaces was assessed. We conclude that In-doped ZnO surfaces should present a higher electronic
response upon adsorption of CO. |
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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 |
000472124700023 |
Publication Date |
2019-04-25 |
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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 |
0022-3697 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
2.059 |
Times cited |
7 |
Open Access |
Not_Open_Access: Available from 26.04.2021
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Notes |
FWO-Vlaanderen, G0D6515N ; ERA.Net RUS Plus, 096 ; VSC; HPC infrastructure of the University of Antwerp; FWO-Vlaanderen; Flemish Government-department EWI; |
Approved |
Most recent IF: 2.059 |
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Call Number |
EMAT @ emat @UA @ admin @ c:irua:159656 |
Serial |
5170 |
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Permanent link to this record |
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Author |
Dixit, H.; Saniz, R.; Lamoen, D.; Partoens, B. |
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Title |
Accurate pseudopotential description of the GW bandstructure of ZnO |
Type |
A1 Journal article |
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Year |
2011 |
Publication |
Computer physics communications |
Abbreviated Journal |
Comput Phys Commun |
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Volume |
182 |
Issue |
9 |
Pages |
2029-2031 |
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Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
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Abstract |
We present the GW band structure of ZnO in its wurtzite (WZ), zincblende (ZB) and rocksalt (RS) phases at the Γ point, calculated within the GW approximation. We have used a Zn20+ pseudopotential which is essential for the adequate treatment of the exchange interaction in the self-energy. The accuracy of the pseudopotential used is also discussed. The effect of the pd hybridization on the GW corrections to the band gap is correlated by comparing the ZB and RS phase. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Amsterdam |
Editor |
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Language |
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Wos |
000292675100062 |
Publication Date |
2011-02-17 |
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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 |
0010-4655; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
3.936 |
Times cited |
18 |
Open Access |
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Notes |
; ; |
Approved |
Most recent IF: 3.936; 2011 IF: 3.268 |
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Call Number |
UA @ lucian @ c:irua:90761 |
Serial |
51 |
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Permanent link to this record |
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Author |
Saniz, R.; Vercauteren, S.; Lamoen, D.; Partoens, B.; Barbiellini, B. |
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Title |
Accurate description of the van der Waals interaction of an electron-positron pair with the surface of a topological insulator |
Type |
P1 Proceeding |
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Year |
2014 |
Publication |
Journal of physics : conference series |
Abbreviated Journal |
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Volume |
505 |
Issue |
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Pages |
012002 |
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Keywords |
P1 Proceeding; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
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Abstract |
Positrons can be trapped in localized states at the surface of a material, and thus quite selectively interact with core or valence surface electrons. Hence, advanced surface positron spectroscopy techniques can present the ideal tools to study a topological insulator, where surface states play a fundamental role. We analyze the problem of a positron at a TI surface, assuming that it is a weakly physisorbed positronium (Ps) atom. To determine if the surface of interest in a material can sustain such a physisorption, an accurate description of the underlying van der Waals (vdW) interaction is essential. We have developed a first-principles parameterfree method, based on the density functional theory, to extract key parameters determining the vdW interaction potential between a Ps atom and the surface of a given material. The method has been successfully applied to quartz and preliminary results on Bi2Te2Se indicate the existence of a positron surface state. We discuss the robustness of our predictions versus the most relevant approximations involved in our approach. |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Bristol |
Editor |
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Language |
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Wos |
000338216500002 |
Publication Date |
2014-04-28 |
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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 |
1742-6588;1742-6596; |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
2 |
Open Access |
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Notes |
; We thank A. Weiss for very useful conversations. We acknowledge financial support from FWO-Vlaanderen (projectG.0150.13). This work was carried out using the HPC infrastructure of the University of Antwerp (CalcUA), adivision of the Flemish Supercomputer Center (VSC), funded by the Hercules foundation and the Flemish Government (EWI Department). B. B. is supported by DOE grants Nos. DE-FG02-07ER46352 and DE-AC02-05CH11231 for theory support at ALS, Berkeley, and a NERSC computer time allocation. ; |
Approved |
Most recent IF: NA |
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Call Number |
UA @ lucian @ c:irua:118264 |
Serial |
46 |
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Permanent link to this record |
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Author |
Callewaert, V.; Saniz, R.; Barbiellini, B.; Partoens, B. |
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Title |
Surface states and positron annihilation spectroscopy: results and prospects from a first-principles approach |
Type |
A1 Journal article |
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Year |
2017 |
Publication |
Journal of physics : conference series |
Abbreviated Journal |
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Volume |
791 |
Issue |
791 |
Pages |
012036 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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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. |
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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 |
000400610500036 |
Publication Date |
2017-02-22 |
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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 |
1742-6588 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
1 |
Open Access |
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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 |
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Call Number |
CMT @ cmt @ c:irua:140847 |
Serial |
4425 |
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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. |
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Title |
New insights into the nanostructure of innovative thin film solar cells gained by positron annihilation spectroscopy |
Type |
A1 Journal article |
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Year |
2017 |
Publication |
Journal of physics : conference series |
Abbreviated Journal |
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Volume |
791 |
Issue |
791 |
Pages |
012021 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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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. |
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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 |
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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 |
1742-6588 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
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Impact Factor |
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Times cited |
1 |
Open Access |
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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 |
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Call Number |
CMT @ cmt @ c:irua:140850 |
Serial |
4426 |
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Permanent link to this record |