| Records |
| Author |
Kim, W.; Covaci, L.; Marsiglio, F. |
| Title |
Impurity scattering of wave packets on a lattice |
Type |
A1 Journal article |
| Year |
2006 |
Publication |
Physical Review B |
Abbreviated Journal |
Phys Rev B |
| Volume |
74 |
Issue |
20 |
Pages |
205120 |
| Keywords |
A1 Journal article |
| Abstract |
Quantum transport in a lattice is distinct from its counterpart in continuum media. Even a free wave packet travels differently in a lattice than in the continuum. We describe quantum scattering in a one-dimensional lattice and illustrate characteristics of quantum transport such as resonant transmission. In particular we examine the transport characteristics of a random trimer model. We demonstrate the real-time propagation of a wave packet and its phase shift due to impurity configurations. Spin-flip scattering is also taken into account in a spin-chain system. We show how individual spins in the chain evolve as a result of a spin-flip interaction between an incoming electron and a spin chain. |
| 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 |
000242409400030 |
Publication Date |
2006-11-27 |
| 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 |
ISBN  |
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Additional Links |
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| Impact Factor |
3.836 |
Times cited |
14 |
Open Access |
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| Notes |
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Approved |
Most recent IF: 3.836; 2006 IF: 3.107 |
| Call Number |
UA @ lucian @ |
Serial |
4428 |
| Permanent link to this record |
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| Author |
Kim, W.; Covaci, L.; Marsiglio, F. |
| Title |
Hidden symmetries of electronic transport in a disordered one-dimensional lattice |
Type |
A1 Journal article |
| Year |
2006 |
Publication |
Physical Review B |
Abbreviated Journal |
Phys Rev B |
| Volume |
73 |
Issue |
19 |
Pages |
195109 |
| Keywords |
A1 Journal article |
| Abstract |
Correlated, or extended, impurities play an important role in the transport properties of dirty metals. Here, we examine, in the framework of a tight-binding lattice, the transmission of a single electron through an array of correlated impurities. In particular we show that particles transmit through an impurity array in identical fashion, regardless of the direction of traversal. The demonstration of this fact is straightforward in the continuum limit, but requires a detailed proof for the discrete lattice. We also briefly demonstrate and discuss the time evolution of these scattering states, to delineate regions (in time and space) where the aforementioned symmetry is violated. |
| 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 |
000237950400042 |
Publication Date |
2006-05-11 |
| 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 |
ISBN |
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Additional Links |
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| Impact Factor |
3.836 |
Times cited |
5 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 3.836; 2006 IF: 3.107 |
| Call Number |
UA @ lucian @ |
Serial |
4429 |
| Permanent link to this record |
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| |
| Author |
Kim, W.; Covaci, L.; Dogan, F.; Marsiglio, F. |
| Title |
Quantum mechanics of spin transfer in coupled electron-spin chains |
Type |
A1 Journal article |
| Year |
2007 |
Publication |
Epl |
Abbreviated Journal |
Epl-Europhys Lett |
| Volume |
79 |
Issue |
6 |
Pages |
67004 |
| Keywords |
A1 Journal article |
| Abstract |
The manner in which spin-polarized electrons interact with a magnetized thin film is currently described by a semi-classical approach. This in turn provides our present understanding of the spin transfer, or spin torque phenomenon. However, spin is an intrinsically quantum-mechanical quantity. Here, we make the first strides towards a fully quantum-mechanical description of spin transfer through spin currents interacting with a Heisenberg-coupled spin chain. Because of quantum entanglement, this requires a formalism based on the density matrix approach. Our description illustrates how individual spins in the chain time-evolve as a result of spin transfer. |
| 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 |
000250409500023 |
Publication Date |
2007-08-24 |
| 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 |
0295-5075 |
ISBN |
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Additional Links |
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| Impact Factor |
1.957 |
Times cited |
3 |
Open Access |
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| Notes |
|
Approved |
Most recent IF: 1.957; 2007 IF: 2.206 |
| Call Number |
UA @ lucian @ |
Serial |
4430 |
| Permanent link to this record |
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| Author |
Covaci, L.; Berciu, M. |
| Title |
Holstein polaron: The effect of coupling to multiple-phonon modes |
Type |
A1 Journal article |
| Year |
2007 |
Publication |
Epl |
Abbreviated Journal |
Epl-Europhys Lett |
| Volume |
80 |
Issue |
6 |
Pages |
67001 |
| Keywords |
A1 Journal article |
| Abstract |
We investigate the effects of coupling to multiple-phonon modes on the properties of a Holstein polaron. To this end, we generalize the Momentum Average approximations MA((0)) and MA((1)) to deal with multiple-phonon modes. As for a single-phonon mode, these approximations are found to be numerically very efficient. They become exact for very weak or very strong couplings, and are highly accurate in the intermediate regimes, e.g. the spectral weights obey exactly the first six, respectively eight, sum rules. Our results show that the effect on ground-state properties is cumulative in nature. As a result, if the effective coupling to one mode is much larger than to all the others, this mode effectively determines the ground-state properties. However, even very weak coupling to a second phonon mode has important non-perturbational effects on the higher-energy spectrum, in particular on the dispersion and the phonon statistics of the polaron band. This has important consequences on the analysis and interpretation of data for real materials. |
| 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 |
000251648300016 |
Publication Date |
2007-11-30 |
| 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 |
0295-5075 |
ISBN |
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Additional Links |
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| Impact Factor |
1.957 |
Times cited |
9 |
Open Access |
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| Notes |
|
Approved |
Most recent IF: 1.957; 2007 IF: 2.206 |
| Call Number |
UA @ lucian @ |
Serial |
4431 |
| Permanent link to this record |
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| Author |
Marchand, D.; Covaci, L.; Berciu, M.; Franz, M. |
| Title |
Giant proximity effect in a phase-fluctuating superconductor |
Type |
A1 Journal article |
| Year |
2008 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys Rev Lett |
| Volume |
101 |
Issue |
9 |
Pages |
097004 |
| Keywords |
A1 Journal article |
| Abstract |
When a tunneling barrier between two superconductors is formed by a normal material that would be a superconductor in the absence of phase fluctuations, the resulting Josephson effect can undergo an enormous enhancement. We establish this novel proximity effect by a general argument as well as a numerical simulation and argue that it may underlie recent experimental observations of the giant proximity effect between two cuprate superconductors separated by a barrier made of the same material rendered normal by severe underdoping. |
| Address |
Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada V6T 1Z1 |
| 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 |
English |
Wos |
000259195800055 |
Publication Date |
2008-08-28 |
| 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 |
0031-9007 |
ISBN |
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Additional Links |
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| Impact Factor |
8.462 |
Times cited |
17 |
Open Access |
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| Notes |
|
Approved |
Most recent IF: 8.462; 2008 IF: 7.180 |
| Call Number |
UA @ lucian @ |
Serial |
4433 |
| Permanent link to this record |
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| Author |
Covaci, L.; Berciu, M. |
| Title |
Polaron formation in the presence of Rashba spin-orbit coupling: implications for spintronics |
Type |
A1 Journal article |
| Year |
2009 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys Rev Lett |
| Volume |
102 |
Issue |
18 |
Pages |
186403 |
| Keywords |
A1 Journal article |
| Abstract |
We study the effects of the Rashba spin-orbit coupling on polaron formation, using a suitable generalization of the momentum average approximation. While previous work on a parabolic band model found that spin-orbit coupling increases the effective mass, we show that the opposite holds for a tight-binding model, unless both the spin-orbit and the electron-phonon couplings are weak. It is thus possible to lower the effective mass of the polaron by increasing the spin-orbit coupling. We also show that when the spin-orbit coupling is large as compared to the phonon energy, the polaron retains only one of the spin-polarized bands in its coherent spectrum. This has major implications for the propagation of spin-polarized currents in such materials, and thus for spintronic applications. |
| Address |
Department of Physics, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z1 |
| 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 |
English |
Wos |
000265948600049 |
Publication Date |
2009-05-08 |
| 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 |
0031-9007 |
ISBN |
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Additional Links |
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| Impact Factor |
8.462 |
Times cited |
25 |
Open Access |
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| Notes |
|
Approved |
Most recent IF: 8.462; 2009 IF: 7.328 |
| Call Number |
UA @ lucian @ |
Serial |
4434 |
| Permanent link to this record |
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| Author |
Andelkovic, M.; Milovanović, S.P.; Covaci, L.; Peeters, F.M. |
| Title |
Double moiré with a twist : supermoiré in encapsulated graphene |
Type |
A1 Journal article |
| Year |
2020 |
Publication |
Nano Letters |
Abbreviated Journal |
Nano Lett |
| Volume |
20 |
Issue |
2 |
Pages |
979 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
| Abstract |
A periodic spatial modulation, as created by a moire pattern, has been extensively studied with the view to engineer and tune the properties of graphene. Graphene encapsulated by hexagonal boron nitride (hBN) when slightly misaligned with the top and bottom hBN layers experiences two interfering moire patterns, resulting in a so-called supermoire (SM). This leads to a lattice and electronic spectrum reconstruction. A geometrical construction of the nonrelaxed SM patterns allows us to indicate qualitatively the induced changes in the electronic properties and to locate the SM features in the density of states and in the conductivity. To emphasize the effect of lattice relaxation, we report band gaps at all Dirac-like points in the hole doped part of the reconstructed spectrum, which are expected to be enhanced when including interaction effects. Our result is able to distinguish effects due to lattice relaxation and due to the interfering SM and provides a clear picture on the origin of recently experimentally observed effects in such trilayer heterostuctures. |
| 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 |
000514255400021 |
Publication Date |
2020-01-21 |
| 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 |
1530-6984 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
10.8 |
Times cited |
33 |
Open Access |
OpenAccess |
| Notes |
; This work was funded by FLAGERA project TRANS2DTMD and the Flemish Science Foundation (FWO-Vl) through a postdoc fellowship for S.P.M. The authors acknowledge useful discussions with W. Zihao and K. Novoselov. ; |
Approved |
Most recent IF: 10.8; 2020 IF: 12.712 |
| Call Number |
UA @ admin @ c:irua:168685 |
Serial |
6490 |
| Permanent link to this record |
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| Author |
Chaves, A.; Covaci, L.; Peeters, F.M.; Milošević, M.V. |
| Title |
Topologically protected moiré exciton at a twist-boundary in a van der Waals heterostructure |
Type |
A1 Journal article |
| Year |
2022 |
Publication |
2D materials |
Abbreviated Journal |
2D Mater |
| Volume |
9 |
Issue |
2 |
Pages |
025012 |
| Keywords |
A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
| Abstract |
A twin boundary in one of the layers of a twisted van der Waals heterostructure separates regions with near opposite inter-layer twist angles. In a MoS<sub>2</sub>/WSe<sub>2</sub>bilayer, the regions with<inline-formula><tex-math><?CDATA $Rh^h$?></tex-math><math overflow=“scroll”><msubsup><mi>R</mi><mi>h</mi><mi>h</mi></msubsup></math><inline-graphic href=“tdmac529dieqn1.gif” type=“simple” /></inline-formula>and<inline-formula><tex-math><?CDATA $Rh^X$?></tex-math><math overflow=“scroll”><msubsup><mi>R</mi><mi>h</mi><mi>X</mi></msubsup></math><inline-graphic href=“tdmac529dieqn2.gif” type=“simple” /></inline-formula>stacking registry that defined the sub-lattices of the moiré honeycomb pattern would be mirror-reflected across such a twist boundary. In that case, we demonstrate that topologically protected chiral moiré exciton states are confined at the twist boundary. These are one-dimensional and uni-directional excitons with opposite velocities for excitons composed by electronic states with opposite valley/spin character, enabling intrinsic, guided, and far reaching valley-polarized exciton currents. |
| 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 |
000760518100001 |
Publication Date |
2022-04-01 |
| 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 |
2053-1583 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
5.5 |
Times cited |
|
Open Access |
OpenAccess |
| Notes |
Fonds Wetenschappelijk Onderzoek; Conselho Nacional de Desenvolvimento Científico e Tecnológico, PQ ; |
Approved |
Most recent IF: 5.5 |
| Call Number |
CMT @ cmt @c:irua:187124 |
Serial |
7046 |
| Permanent link to this record |
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| Author |
Kourmoulakis, G.; Michail, A.; Paradisanos, I.; Marie, X.; Glazov, M.M.; Jorissen, B.; Covaci, L.; Stratakis, E.; Papagelis, K.; Parthenios, J.; Kioseoglou, G. |
| Title |
Biaxial strain tuning of exciton energy and polarization in monolayer WS2 |
Type |
A1 Journal Article |
| Year |
2023 |
Publication |
Applied Physics Letters |
Abbreviated Journal |
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| Volume |
123 |
Issue |
22 |
Pages |
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| Keywords |
A1 Journal Article; Condensed Matter Theory (CMT) ; |
| Abstract |
We perform micro-photoluminescence and Raman experiments to examine the impact of biaxial tensile strain on the optical properties of WS2 monolayers. A strong shift on the order of −130 meV per % of strain is observed in the neutral exciton emission at room temperature. Under near-resonant excitation, we measure a monotonic decrease in the circular polarization degree under the applied strain. We experimentally separate the effect of the strain-induced energy detuning and evaluate the pure effect coming from the biaxial strain. The analysis shows that the suppression of the circular polarization degree under the biaxial strain is related to an interplay of energy and polarization relaxation channels as well as to variations in the exciton oscillator strength affecting the long-range exchange interaction. |
| 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 |
001124156400003 |
Publication Date |
2023-11-27 |
| 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 |
0003-6951 |
ISBN |
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Additional Links |
UA library record; WoS full record |
| Impact Factor |
4 |
Times cited |
|
Open Access |
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| Notes |
Hellenic Foundation for Research and Innovation, HFRI-FM17-3034 ; |
Approved |
Most recent IF: 4; 2023 IF: 3.411 |
| Call Number |
CMT @ cmt @c:irua:202178 |
Serial |
8991 |
| Permanent link to this record |
