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Aucar Boidi, N.; Fernández García, H.; Nunez-Fernandez, Y.; Hallberg, K. |
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Title |
In-gap band in the one-dimensional two-orbital Kanamori-Hubbard model with interorbital Coulomb interaction |
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A1 Journal article |
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Year  |
2021 |
Publication |
Physical review research |
Abbreviated Journal |
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Volume |
3 |
Issue |
4 |
Pages |
043213 |
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Keywords |
A1 Journal article; AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Antwerp X-ray Imaging and Spectroscopy (AXIS) |
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Abstract |
We study the electronic spectral properties at zero temperature of the one-dimensional (1D) version of the degenerate two-orbital Kanamori-Hubbard model, one of the well-established frameworks to study transition metal compounds, using state-of-the-art numerical techniques based on the density matrix renormalization group. While the system is Mott insulating for the half-filled case, as expected for an interacting 1D system, we find interesting and rich structures in the single-particle density of states (DOS) for the hole-doped system. In particular, we find the existence of in-gap states which are pulled down to lower energies from the upper Hubbard band with increasing the interorbital Coulomb interaction V. We analyze the composition of the DOS by projecting it onto different local excitations, and we observe that for large dopings these in-gap excitations are formed mainly by interorbital holon-doublon (HD) states and their energies follow approximately the HD states in the atomic limit. We observe that the Hund interaction J increases the width of the in-gap band, as expected from the two-particle fluctuations in the Hamiltonian. The observation of a finite density of states within the gap between the Hubbard bands for this extended 1D model indicates that these systems present a rich excitation spectra which could help us understand the microscopic physics behind multiorbital compounds. |
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000736651500002 |
Publication Date |
2021-12-23 |
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UA library record; WoS full record; WoS citing articles |
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OpenAccess |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:184836 |
Serial |
8073 |
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Author |
Tiwari, S.; Vanherck, J.; Van de Put, M.L.; Vandenberghe, W.G.; Sorée, B. |
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Title |
Computing Curie temperature of two-dimensional ferromagnets in the presence of exchange anisotropy |
Type |
A1 Journal article |
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Year |
2021 |
Publication |
Physical review research |
Abbreviated Journal |
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Volume |
3 |
Issue |
4 |
Pages |
043024 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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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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000707506500001 |
Publication Date |
2021-10-11 |
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OpenAccess |
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Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:182522 |
Serial |
6975 |
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Benito Llorens, J.; Embon, L.; Correa, A.; Gonzalez, J.D.; Herrera, E.; Guillamon, I.; Luccas, R.F.; Azpeitia, J.; Mompean, F.J.; Garcia-Hernandez, M.; Munuera, C.; Aragon Sanchez, J.; Fasano, Y.; Milošević, M.V.; Suderow, H.; Anahory, Y. |
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Title |
Observation of a gel of quantum vortices in a superconductor at very low magnetic fields |
Type |
A1 Journal article |
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Year |
2020 |
Publication |
Physical review research |
Abbreviated Journal |
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2 |
Issue |
1 |
Pages |
013329 |
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Keywords |
A1 Journal article; Condensed Matter Theory (CMT) |
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Abstract |
A gel consists of a network of particles or molecules formed for example using the sol-gel process, by which a solution transforms into a porous solid. Particles or molecules in a gel are mainly organized on a scaffold that makes up a porous system. Quantized vortices in type-II superconductors mostly form spatially homogeneous ordered or amorphous solids. Here we present high-resolution imaging of the vortex lattice displaying dense vortex clusters separated by sparse or entirely vortex-free regions in beta-Bi2Pd superconductor. We find that the intervortex distance diverges upon decreasing the magnetic field and that vortex lattice images follow a multifractal behavior. These properties, characteristic of gels, establish the presence of a novel vortex distribution, distinctly different from the well-studied disordered and glassy phases observed in high-temperature and conventional superconductors. The observed behavior is caused by a scaffold of one-dimensional structural defects with enhanced stress close to the defects. The vortex gel might often occur in type-II superconductors at low magnetic fields. Such vortex distributions should allow to considerably simplify control over vortex positions and manipulation of quantum vortex states. |
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000602698100008 |
Publication Date |
2020-03-18 |
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14 |
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Notes |
; We acknowledge support, discussions and critical reading of the manuscript from Eli Zeldov, who also devised and setup the SOT system. We also acknowledge critical reading and suggestions of Vladimir Kogan and Alexander Buzdin. Work performed in Spain was supported by the MINECO (FIS2017-84330-R, MAT2017-87134-C2-2-R, RYC-2014-16626 and RYC-2014-15093) and by the Region of Madrid through programs NANOFRONTMAG-CM (S2013/MIT-2850) and MAD2D-CM (S2013/ MIT-3007). The SEGAINVEX at UAM is also acknowledged as well as PEOPLE, Graphene Flagship, NMP programs of EU (Grant Agreements FP7-PEOPLE-2013-CIG 618321, 604391 and AMPHIBIAN H2020-NMBP-03-2016 NMP3-SL 2012-310516). Work in Israel was supported by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant No. 802952). Y.F. acknowledges the support of grant PICT 2017-2182 from the ANPCyT. R.F.L. acknowledges the support of grant PICT 2017-2898 from the ANPCyT. E.H. acknowledges support of Departamento Administrativo de Ciencia, Tecnologia e Innovacion, COLCIENCIAS (Colombia) Programa de estancias Postdoctorales convocatoria 784-2017 and the Cluster de investigacin en ciencias y tecnologas convergentes de la Universidad Central (Colombia). I.G. was supported by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant No. 679080). M.V.M. acknowledges support from Research FoundationFlanders (FWO). The international collaboration on this work was fostered by the EU-COST Action CA16218 Nanoscale Coherent Hybrid Devices for Superconducting Quantum Technologies (NANOCOHYBRI). J.D.G. and M.V.M. gratefully acknowledge support from the Research Fund (FONCIENCIAS) of Universidad del Magdalena. ; |
Approved |
Most recent IF: NA |
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Call Number |
UA @ admin @ c:irua:175138 |
Serial |
6694 |
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