| Records |
| Author |
Garcia, J.H.; Covaci, L.; Rappoport, T.G. |
| Title |
Real-space calculation of the conductivity tensor for disordered topological matter |
Type |
A1 Journal article |
| Year |
2015 |
Publication |
Physical review letters |
Abbreviated Journal  |
Phys Rev Lett |
| Volume |
114 |
Issue |
114 |
Pages |
116602 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
We describe an efficient numerical approach to calculate the longitudinal and transverse Kubo conductivities of large systems using Bastin's formulation. We expand the Green's functions in terms of Chebyshev polynomials and compute the conductivity tensor for any temperature and chemical potential in a single step. To illustrate the power and generality of the approach, we calculate the conductivity tensor for the quantum Hall effect in disordered graphene and analyze the effect of the disorder in a Chern insulator in Haldane's model on a honeycomb lattice. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
New York, N.Y. |
Editor |
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| Language |
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Wos |
000351430600010 |
Publication Date |
2015-03-20 |
| 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 |
|
Edition |
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| ISSN |
0031-9007;1079-7114; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
8.462 |
Times cited |
69 |
Open Access |
|
| Notes |
; We acknowledge A. R. Hernandez, A. Ferreira, and E. Mucciolo for discussions. T. G. R and J. H. G acknowledge the Brazilian agencies CNPq, FAPERJ, and INCT de Nanoestruturas de Carbono for financial support. L. C. acknowledges the Flemish Science Foundation (FWO-Vlaanderen) for financial support. ; |
Approved |
Most recent IF: 8.462; 2015 IF: 7.512 |
| Call Number |
c:irua:125467 |
Serial |
2827 |
| Permanent link to this record |
| |
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| |
| Author |
Berdiyorov, G.R.; Milošević, M.V.; Covaci, L.; Peeters, F.M. |
| Title |
Rectification by an imprinted phase in a Josephson junction |
Type |
A1 Journal article |
| Year |
2011 |
Publication |
Physical review letters |
Abbreviated Journal |
Phys Rev Lett |
| Volume |
107 |
Issue |
17 |
Pages |
177008-177008,5 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
A Josephson phase shift can be induced in a Josephson junction by a strategically nearby pinned Abrikosov vortex (AV). For an asymmetric distribution of an imprinted phase along the junction (controlled by the position of the AV) such a simple system is capable of rectification of ac current in a broad and tunable frequency range. The resulting rectified voltage is a consequence of the directed motion of a Josephson antivortex which forms a pair with the AV when at local equilibrium. The proposed realization of the ratchet potential by an imprinted phase is more efficient than the asymmetric geometry of the junction itself, is easily realizable experimentally, and provides rectification even in the absence of an applied magnetic field. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
New York, N.Y. |
Editor |
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| Language |
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Wos |
000296985000008 |
Publication Date |
2011-10-21 |
| 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 |
|
Edition |
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| ISSN |
0031-9007;1079-7114; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
8.462 |
Times cited |
28 |
Open Access |
|
| Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vlaanderen) and the Belgian Science Policy (IAP). G. R. B. and L. C. acknowledge individual support from FWO-Vlaanderen. ; |
Approved |
Most recent IF: 8.462; 2011 IF: 7.370 |
| Call Number |
UA @ lucian @ c:irua:93715 |
Serial |
2847 |
| Permanent link to this record |
| |
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| |
| Author |
Zhang, L.-F.; Covaci, L.; Milošević, M.V.; Berdiyorov, G.R.; Peeters, F.M. |
| Title |
Unconventional vortex states in nanoscale superconductors due to shape-induced resonances in the inhomogeneous Cooper-pair condensate |
Type |
A1 Journal article |
| Year |
2012 |
Publication |
Physical review letters |
Abbreviated Journal |
Phys Rev Lett |
| Volume |
109 |
Issue |
10 |
Pages |
107001 |
| Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
| Abstract |
Vortex matter in mesoscopic superconductors is known to be strongly affected by the geometry of the sample. Here we show that in nanoscale superconductors with coherence length comparable to the Fermi wavelength the shape resonances of the order parameter results in an additional contribution to the quantum topological confinement-leading to unconventional vortex configurations. Our Bogoliubov-de Gennes calculations in a square geometry reveal a plethora of asymmetric, giant multivortex, and vortex-antivortex structures, stable over a wide range of parameters and which are very different from those predicted by the Ginzburg-Landau theory. These unconventional states are relevant for high-T-c nanograins, confined Bose-Einstein condensates, and graphene flakes with proximity-induced superconductivity. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
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Place of Publication |
New York, N.Y. |
Editor |
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| Language |
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Wos |
000308295700014 |
Publication Date |
2012-09-05 |
| 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;1079-7114; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
8.462 |
Times cited |
31 |
Open Access |
|
| Notes |
; This work was supported by the Flemish Science Foundation (FWO-Vlaanderen). ; |
Approved |
Most recent IF: 8.462; 2012 IF: 7.943 |
| Call Number |
UA @ lucian @ c:irua:101850 |
Serial |
3801 |
| Permanent link to this record |
| |
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| |
| Author |
Covaci, L.; Berciu, M. |
| Title |
Survival of the Dirac points in rippled graphene |
Type |
A1 Journal article |
| Year |
2008 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys Rev Lett |
| Volume |
100 |
Issue |
25 |
Pages |
256405 |
| Keywords |
A1 Journal article; Electron Microscopy for Materials Science (EMAT); |
| Abstract |
We study the effects of the rippling of a graphene sheet on quasiparticle dispersion. This is achieved using a generalization to the honeycomb lattice of the momentum average approximation, which is accurate for all coupling strengths and at all energies. We show that even though the position of the Dirac points may move and the Fermi speed can be renormalized significantly, quasiparticles with very long lifetimes survive near the Dirac points even for very strong couplings. |
| Address |
Department of Physics and Astronomy, 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 |
000257230500047 |
Publication Date |
2008-06-26 |
| 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 |
15 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 8.462; 2008 IF: 7.180 |
| Call Number |
UA @ lucian @ |
Serial |
4010 |
| Permanent link to this record |
| |
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| |
| Author |
Goodvin, G.L.; Covaci, L.; Berciu, M. |
| Title |
Holstein polarons near surfaces |
Type |
A1 Journal article |
| Year |
2009 |
Publication |
Physical Review Letters |
Abbreviated Journal |
Phys Rev Lett |
| Volume |
103 |
Issue |
17 |
Pages |
176402 |
| Keywords |
A1 Journal article |
| Abstract |
We study the effects of a nearby surface on the spectral weight of a Holstein polaron, using the inhomogeneous momentum average approximation which is accurate over the entire range of electron-phonon (e-ph) coupling strengths. The broken translational symmetry is taken into account exactly. We find that the e-ph coupling gives rise to a large additional surface potential, with strong retardation effects, which may bind surface states even when they are not normally expected. The surface, therefore, has a significant effect and bulk properties are recovered only very far away from it. These results demonstrate that interpretation in terms of bulk quantities of spectroscopic data sensitive only to a few surface layers is not always appropriate. |
| Address |
Department of Physics and Astronomy, 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 |
000271164500042 |
Publication Date |
2009-10-22 |
| 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 |
8 |
Open Access |
|
| Notes |
|
Approved |
Most recent IF: 8.462; 2009 IF: 7.328 |
| Call Number |
UA @ lucian @ |
Serial |
4435 |
| 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 |
|
Additional Links |
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| Impact Factor |
8.462 |
Times cited |
17 |
Open Access |
|
| 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 |
|
| 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 |
Joao, S.M.; Andelkovic, M.; Covaci, L.; Rappoport, T.G.; Lopes, J.M.V.P.; Ferreira, A. |
| Title |
KITE : high-performance accurate modelling of electronic structure and response functions of large molecules, disordered crystals and heterostructures |
Type |
A1 Journal article |
| Year |
2020 |
Publication |
Royal Society Open Science |
Abbreviated Journal |
Roy Soc Open Sci |
| Volume |
7 |
Issue |
2 |
Pages |
191809-191832 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT) |
| Abstract |
We present KITE, a general purpose open-source tight-binding software for accurate real-space simulations of electronic structure and quantum transport properties of large-scale molecular and condensed systems with tens of billions of atomic orbitals (N similar to 10(10)). KITE's core is written in C++, with a versatile Python-based interface, and is fully optimized for shared memory multi-node CPU architectures, thus scalable, efficient and fast. At the core of KITE is a seamless spectral expansion of lattice Green's functions, which enables large-scale calculations of generic target functions with uniform convergence and fine control over energy resolution. Several functionalities are demonstrated, ranging from simulations of local density of states and photo-emission spectroscopy of disordered materials to large-scale computations of optical conductivity tensors and real-space wave-packet propagation in the presence of magneto-static fields and spin-orbit coupling. On-the-fly calculations of real-space Green's functions are carried out with an efficient domain decomposition technique, allowing KITE to achieve nearly ideal linear scaling in its multi-threading performance. Crystalline defects and disorder, including vacancies, adsorbates and charged impurity centres, can be easily set up with KITE's intuitive interface, paving the way to user-friendly large-scale quantum simulations of equilibrium and non-equilibrium properties of molecules, disordered crystals and heterostructures subject to a variety of perturbations and external conditions. |
| 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 |
000518020200001 |
Publication Date |
2020-02-26 |
| 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 |
2054-5703 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
3.5 |
Times cited |
19 |
Open Access |
OpenAccess |
| Notes |
; T.G.R. and A.F. acknowledge support from the Newton Fund and the Royal Society through the Newton Advanced Fellowship scheme (ref. no. NA150043). M.A. and L.C. acknowledge support from the Trans2DTMD FlagEra project and the VSC (Flemish Supercomputer Center). A.F. acknowledges support from the Royal Society through a University Research Fellowship (ref. nos. UF130385 and URF-R-191021) and an Enhancement Award (ref. no. RGF-EA-180276). T.G.R. acknowledges the support from the Brazilian agencies CNPq and FAPERJ and COMPETE2020, PORTUGAL2020, FEDER and the Portuguese Foundation for Science and Technology (FCT) through project POCI-01-0145-FEDER-028114. S.M.J. is supported by Fundacao para a Ciencia e Tecnologia (FCT) under the grant no. PD/BD/142798/ 2018. S.M.J. and J.M.V.P.L. acknowledge financial support from the FCT, COMPETE 2020 programme in FEDER component (European Union), through projects POCI-01-0145-FEDER028887 and UID/FIS/04650/2013. S.M.J. and J.M.V.P.L. further acknowledge financial support from FCT through national funds, co-financed by COMPETE-FEDER (grant no. M-ERANET2/0002/2016 -UltraGraf) under the Partnership Agreement PT2020. ; |
Approved |
Most recent IF: 3.5; 2020 IF: 2.243 |
| Call Number |
UA @ admin @ c:irua:167751 |
Serial |
6556 |
| Permanent link to this record |
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| Author |
Lin, S.-H.; Milošević, M.V.; Covaci, L.; Janko, B.; Peeters, F.M. |
| Title |
Quantum rotor in nanostructured superconductors |
Type |
A1 Journal article |
| Year |
2014 |
Publication |
Scientific reports |
Abbreviated Journal |
Sci Rep-Uk |
| Volume |
4 |
Issue |
|
Pages |
4542-4546 |
| Keywords |
A1 Journal article; Engineering sciences. Technology; Condensed Matter Theory (CMT) |
| Abstract |
Despite its apparent simplicity, the idealized model of a particle constrained to move on a circle has intriguing dynamic properties and immediate experimental relevance. While a rotor is rather easy to set up classically, the quantum regime is harder to realize and investigate. Here we demonstrate that the quantum dynamics of quasiparticles in certain classes of nanostructured superconductors can be mapped onto a quantum rotor. Furthermore, we provide a straightforward experimental procedure to convert this nanoscale superconducting rotor into a regular or inverted quantum pendulum with tunable gravitational field, inertia, and drive. We detail how these novel states can be detected via scanning tunneling spectroscopy. The proposed experiments will provide insights into quantum dynamics and quantum chaos. |
| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
Nature Publishing Group |
Place of Publication |
London |
Editor |
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| Language |
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Wos |
000333555300007 |
Publication Date |
2014-04-01 |
| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
2045-2322; |
ISBN |
|
Additional Links |
UA library record; WoS full record; WoS citing articles |
| Impact Factor |
4.259 |
Times cited |
4 |
Open Access |
|
| Notes |
; The work was supported by the Flemish Science Foundation (FWO-Vl), the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract W-31-109-Eng-38, and the US National Science Foundation via NSF-NIRT ECS-0609249. ; |
Approved |
Most recent IF: 4.259; 2014 IF: 5.578 |
| Call Number |
UA @ lucian @ c:irua:116848 |
Serial |
2785 |
| Permanent link to this record |
