In: Physical Review Letters, 2021, vol. 126, no. 15, p. 157401
Terahertz vortex beams with different superposition of the orbital angular momentum $l={\pm}1$, ${\pm}2$, ${\pm}3$, and ${\pm}4$ and spin angular momentum ${\sigma}={\pm}1$ were used to study antiferromagnetic (AFM) resonances in TbFe$_3$(BO$_3$)$_4$ and Ni$_3$TeO$_6$ single crystals. In both materials we observed a strong vortex beam dichroism for the AFM resonances that are split in ...
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In: Physical Review B, 2020, vol. 102, no. 2020-24, p. 241103
Recent experiments demonstrate the induction of long-range order in correlated electron systems via external perturbations, which calls for a better understanding of nonthermal ordered states and nonequilibrium symmetry breaking. Here, we reveal a mechanism based on entropy cooling and entropy trapping in a strongly correlated multiorbital system. We consider a two-orbital Hubbard model with...
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In: Computer Physics Communications, 2020, vol. 257, no. 2020, p. 107484
The nonequilibrium dynamics of correlated many-particle systems is of interest in connection with pump–probe experiments on molecular systems and solids, as well as theoretical investigations of transport properties and relaxation processes. Nonequilibrium Green’s functions are a powerful tool to study interaction effects in quantum many-particle systems out of equilibrium, and to extract...
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In: Physical Review B, 2020, vol. 102, no. 19, p. 195103
An antiferromagnetic Hund coupling in multiorbital Hubbard systems induces orbital freezing and an associated superconducting instability, as well as unique composite orders in the case of an odd number of orbitals. While the rich phase diagram of the half-filled three-orbital model has recently been explored in detail, the properties of the doped system remain to be clarified. Here, we...
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In: Physical Review B, 2020, vol. 102, no. 8, p. 081121
We study high-harmonic generation in two-dimensional electron systems with Rashba and Dresselhaus spin-orbit coupling and derive harmonic generation selection rules with the help of group theory. Based on the band structures of these minimal models and explicit simulations we reveal how the spin-orbit parameters control the cutoff energy in the high-harmonic spectrum. We also show that the...
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In: Physical Review B, 2020, vol. 102, no. 8, p. 085102
The Hund's coupling in multiorbital Hubbard systems induces spin freezing and associated Hund metal behavior. Using dynamical mean-field theory, we explore the effect of local moment formation, spin, and charge excitations on the entropy and specific heat of the three-orbital model. For fillings 2≲n<3 and low temperature, we demonstrate a substantial enhancement of the entropy in the...
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In: Nature Physics, 2020, p. -
Nd2Ir2O7 is a correlated semimetal with the pyrochlore structure, in which competing spin–orbit coupling and electron–electron interactions are believed to induce a time- reversal symmetry-broken Weyl semimetal phase characterized by pairs of topologically protected Dirac points at the Fermi energy1,2,3,4. However, the emergent properties in these materials are far from clear, and exotic...
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In: Physical Review B, 2020, vol. 101, no. 19, p. 195139
The high-harmonic spectrum of the Mott insulating Hubbard model has recently been shown to exhibit plateau structures with cutoff energies determined by nth-nearest- neighbor doublon-holon recombination processes. The spectrum thus allows one to extract the on-site repulsion U. Here, we consider generalizations of the single-band Hubbard model and discuss the signatures of bosonic excitations...
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In: Physical Review B, 2020, vol. 101, no. 19, p. 195118
We consider a two-band spinless model describing an excitonic insulator (EI) on the two-dimensional square lattice with anisotropic hopping parameters and electron-phonon (el-ph) coupling, inspired by the EI candidate Ta2NiSe5. We systematically study the nature of the collective excitations in the ordered phase which originates from the interband Coulomb interaction and the el-ph coupling. ...
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In: Physical Review B, 2020, vol. 101, no. 3, p. 035203
We study the time evolution of excitonic states after photoexcitation in the one- dimensional spinless extended Falicov-Kimball model. Several numerical methods are employed and benchmarked against each other: time-dependent mean-field simulations, the second-Born approximation (2BA) within the Kadanoff-Baym formalism, the generalized Kadanoff-Baym ansatz (GKBA) implemented with the 2BA, and...
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