Records |
Author |
Vanherck, J.; Schulenborg, J.; Saptsov, R.B.; Splettstoesser, J.; Wegewijs, M.R. |
Title |
Relaxation of quantum dots in a magnetic field at finite bias -Charge, spin, and heat currents |
Type |
A1 Journal article |
Year |
2017 |
Publication |
Physica status solidi: B: basic research |
Abbreviated Journal |
Phys Status Solidi B |
Volume |
254 |
Issue |
3 |
Pages |
Unsp 1600614 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
<script type='text/javascript'>document.write(unpmarked('We perform a detailed study of the effect of finite bias and magnetic field on the tunneling-induced decay of the state of a quantum dot by applying a recently discovered general duality [Phys. Rev. B 93, 81411 (2016)]. This duality provides deep physical insight into the decay dynamics of electronic open quantum systems with strong Coulomb interaction. It associates the amplitudes of decay eigenmodes of the actual system to the eigenmodes of a so-called dual system with attractive interaction. Thereby, it predicts many surprising features in the transient transport and its dependence on experimental control parameters: the attractive interaction of the dual model shows up as sharp features in the amplitudes of measurable time-dependent currents through the actual repulsive system. In particular, for interacting quantum dots, the time-dependent heat current exhibits a decay mode that dissipates the interaction energy and that is tied to the fermion parity of the system. We show that its decay amplitude has an unexpected gate-voltage dependence that is robust up to sizable bias voltages and then bifurcates, reflecting that the Coulomb blockade is lifted in the dual system. Furthermore, combining our duality relation with the known Iche-duality, we derive new symmetry properties of the decay rates as a function of magnetic field and gate voltage. Finally, we quantify charge- and spin-mode mixing due to the magnetic field using a single mixing parameter.')); |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
Berlin |
Editor |
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Language |
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Wos |
000395441500011 |
Publication Date |
2017-01-18 |
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 |
0370-1972 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
1.674 |
Times cited |
4 |
Open Access ![sorted by Open Access field, ascending order (up)](img/sort_asc.gif) |
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Notes |
; We acknowledge the financial support of Erasmus Mundus (J. V.), DFG project SCHO 641/7-1 (R.B.S. and M.R.W), the Swedish VR (J.Sc., J.Sp.), and the Knut and Alice Wallenberg Foundation (J. Sp.). The authors thank F. Haupt and N. Dittmann for useful discussions on the topic. ; |
Approved |
Most recent IF: 1.674 |
Call Number |
UA @ lucian @ c:irua:142510 |
Serial |
4894 |
Permanent link to this record |
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Author |
Schulenborg, J.; Di Marco, A.; Vanherck, J.; Wegewijs, M.R.; Splettstoesser, J. |
Title |
Thermoelectrics of interacting nanosystems-exploiting superselection instead of time-reversal symmetry |
Type |
A1 Journal article |
Year |
2017 |
Publication |
Entropy: an international and interdisciplinary journal of entropy and information studies |
Abbreviated Journal |
Entropy-Switz |
Volume |
19 |
Issue |
12 |
Pages |
668 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
<script type='text/javascript'>document.write(unpmarked('Thermoelectric transport is traditionally analyzed using relations imposed by time-reversal symmetry, ranging from Onsager\u0027s results to fluctuation relations in counting statistics. In this paper, we show that a recently discovered duality relation for fermionic systems-deriving from the fundamental fermion-parity superselection principle of quantum many-particle systems-provides new insights into thermoelectric transport. Using a master equation, we analyze the stationary charge and heat currents through a weakly coupled, but strongly interacting single-level quantum dot subject to electrical and thermal bias. In linear transport, the fermion-parity duality shows that features of thermoelectric response coefficients are actually dominated by the average and fluctuations of the charge in a dual quantum dot system, governed by attractive instead of repulsive electron-electron interaction. In the nonlinear regime, the duality furthermore relates most transport coefficients to much better understood equilibrium quantities. Finally, we naturally identify the fermion-parity as the part of the Coulomb interaction relevant for both the linear and nonlinear Fourier heat. Altogether, our findings hence reveal that next to time-reversal, the duality imposes equally important symmetry restrictions on thermoelectric transport. As such, it is also expected to simplify computations and clarify the physical understanding for more complex systems than the simplest relevant interacting nanostructure model studied here.')); |
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 |
000419007900037 |
Publication Date |
2017-12-06 |
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 |
1099-4300 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
1.821 |
Times cited |
3 |
Open Access ![sorted by Open Access field, ascending order (up)](img/sort_asc.gif) |
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Notes |
; We thank Rafael Sanchez for useful comments on the manuscript. We acknowledge funding from the Knut and Alice Wallenberg foundation through their Academy Fellows program (J.Sp. and A.D.M.), from the Swedish VR (J.Sp. and J.Sc.), from the Erasmus Mundus program (J.V.), and from the DFG project SCHO 641/7-1 (M.R.W.). ; |
Approved |
Most recent IF: 1.821 |
Call Number |
UA @ lucian @ c:irua:148548 |
Serial |
4900 |
Permanent link to this record |
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Author |
Vanherck, J.; Sorée, B.; Magnus, W. |
Title |
Anisotropic bulk and planar Heisenberg ferromagnets in uniform, arbitrarily oriented magnetic fields |
Type |
A1 Journal article |
Year |
2018 |
Publication |
Journal of physics : condensed matter |
Abbreviated Journal |
J Phys-Condens Mat |
Volume |
30 |
Issue |
27 |
Pages |
275801 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
Today, further downscaling of mobile electronic devices poses serious problems, such as energy consumption and local heat dissipation. In this context, spin wave majority gates made of very thin ferromagnetic films may offer a viable alternative. However, similar downscaling of magnetic thin films eventually enforces the latter to operate as quasi-2D magnets, the magnetic properties of which are not yet fully understood, especially those related to anisotropies and external magnetic fields in arbitrary directions. To this end, we have investigated the behaviour of an easy-plane and easy-axis anisotropic ferromagnet-both in two and three dimensions-subjected to a uniform magnetic field, applied along an arbitrary direction. In this paper, a spin-1/2 Heisenberg Hamiltonian with anisotropic exchange interactions is solved using double-time temperature-dependent Green's functions and the Tyablikov decoupling approximation. We determine various magnetic properties such as the Curie temperature and the magnetization as a function of temperature and the applied magnetic field, discussing the impact of the system's dimensionality and the type of anisotropy. The magnetic reorientation transition taking place in anisotropic Heisenberg ferromagnets is studied in detail. Importantly, spontaneous magnetization is found to be absent for easy-plane 2D spin systems with short range interactions. |
Address |
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Corporate Author |
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Thesis |
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Publisher |
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Place of Publication |
London |
Editor |
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Language |
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Wos |
000434980600001 |
Publication Date |
2018-05-21 |
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 |
0953-8984 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
2.649 |
Times cited |
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Open Access ![sorted by Open Access field, ascending order (up)](img/sort_asc.gif) |
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Notes |
; ; |
Approved |
Most recent IF: 2.649 |
Call Number |
UA @ lucian @ c:irua:151945UA @ admin @ c:irua:151945 |
Serial |
5012 |
Permanent link to this record |
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Author |
Vanherck, J.; Bacaksiz, C.; Sorée, B.; Milošević, M.V.; Magnus, W. |
Title |
2D ferromagnetism at finite temperatures under quantum scrutiny |
Type |
A1 Journal article |
Year |
2020 |
Publication |
Applied Physics Letters |
Abbreviated Journal |
Appl Phys Lett |
Volume |
117 |
Issue |
5 |
Pages |
052401 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
Recent years have seen a tremendous rise of two-dimensional (2D) magnetic materials, several of which were verified experimentally. However, most of the theoretical predictions to date rely on ab initio methods, at zero temperature and fluctuation-free, while one certainly expects detrimental quantum fluctuations at finite temperatures. Here, we present the solution of the quantum Heisenberg model for honeycomb/hexagonal lattices with anisotropic exchange interaction up to third nearest neighbors and in an applied field in arbitrary direction, which answers the question whether long-range magnetization can indeed survive in the ultrathin limit of materials, up to which temperature, and what the characteristic excitation (magnon) frequencies are, all essential to envisaged applications of magnetic 2D materials. We find that long-range magnetic order persists at finite temperature for materials with overall easy-axis anisotropy. We validate the calculations on the examples of monolayers CrI3, CrBr3, and MnSe2. Moreover, we provide an easy-to-use tool to calculate Curie temperatures of new 2D computational materials. |
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Thesis |
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Place of Publication |
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Editor |
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Language |
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Wos |
000559330100001 |
Publication Date |
2020-08-03 |
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; 1077-3118 |
ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
4 |
Times cited |
8 |
Open Access ![sorted by Open Access field, ascending order (up)](img/sort_asc.gif) |
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Notes |
; This work was supported by the Research Foundation-Flanders (FWO) and the special research funds of the University of Antwerp (BOF-UA). ; |
Approved |
Most recent IF: 4; 2020 IF: 3.411 |
Call Number |
UA @ admin @ c:irua:171176 |
Serial |
6445 |
Permanent link to this record |
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Author |
Vanherck, J. |
Title |
Spontaneous and induced magnetisation in two-dimensional and bulk Heisenberg ferromagnets : a quantum mechanical treatment |
Type |
Doctoral thesis |
Year |
2020 |
Publication |
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Abbreviated Journal |
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Volume |
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Issue |
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Pages |
160 p. |
Keywords |
Doctoral thesis; Condensed Matter Theory (CMT) |
Abstract |
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Series Title |
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Additional Links |
UA library record |
Impact Factor |
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Times cited |
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Open Access ![sorted by Open Access field, ascending order (up)](img/sort_asc.gif) |
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Notes |
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Approved |
Most recent IF: NA |
Call Number |
UA @ admin @ c:irua:171875 |
Serial |
6612 |
Permanent link to this record |
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Author |
Tiwari, S.; Vanherck, J.; Van de Put, M.L.; Vandenberghe, W.G.; Sorée, B. |
Title |
Computing Curie temperature of two-dimensional ferromagnets in the presence of exchange anisotropy |
Type |
A1 Journal article |
Year |
2021 |
Publication |
Physical review research |
Abbreviated Journal |
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Volume |
3 |
Issue |
4 |
Pages |
043024 |
Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
Abstract |
We compare three first-principles methods of calculating the Curie temperature in two-dimensional (2D) ferromagnetic materials (FM), modeled using the Heisenberg model, and propose a simple formula for estimating the Curie temperature with high accuracy that works for all common 2D lattice types. First, we study the effect of exchange anisotropy on the Curie temperature calculated using the Monte Carlo (MC), the Green's function, and the renormalized spin-wave (RNSW) methods. We find that the Green's function method overestimates the Curie temperature in high-anisotropy regimes compared to the MC method, whereas the RNSW method underestimates the Curie temperature compared to the MC and the Green's function methods. Next, we propose a closed-form formula for calculating the Curie temperature of 2D FMs, which provides an estimate of the Curie temperature that is greatly improved over the mean-field expression for magnetic material screening. We apply the closed-form formula to predict the Curie temperature 2D magnets screened from the C2DB database and discover several high Curie temperature FMs, with Fe2F2 and MoI2 emerging as the most promising 2D ferromagnets. Finally, by comparing to experimental results for CrI3, CrCl3, and CrBr3, we conclude that for small effective anisotropies, the Green's-function-based equations are preferable, while for larger anisotropies, MC-based results are more predictive. |
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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 |
000707506500001 |
Publication Date |
2021-10-11 |
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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 |
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ISBN |
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Additional Links |
UA library record; WoS full record; WoS citing articles |
Impact Factor |
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Times cited |
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Open Access ![sorted by Open Access field, ascending order (up)](img/sort_asc.gif) |
OpenAccess |
Notes |
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Approved |
Most recent IF: NA |
Call Number |
UA @ admin @ c:irua:182522 |
Serial |
6975 |
Permanent link to this record |