In: Journal of Superconductivity and Novel Magnetism, 2015, vol. 28, no. 4, p. 1231-1236
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In: Physical Review B, 2020, vol. 101, no. 22, p. 224515
The magnetic and superconducting properties of a series of underdoped Ba 1 − x Na x Fe 2 As 2 (BNFA) single crystals with 0.19 ≤ x ≤ 0.34 have been investigated with the complementary muon-spin-rotation ( μ SR ) and infrared spectroscopy techniques. The focus has been on the different antiferromagnetic states in the underdoped regime and their competition with superconductivity,...
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In: Physical Review B, 2020, vol. 102, no. 16, p. 165136
We show that a metastable η-pairing superconducting phase can be induced by photodoping doublons and holes into a strongly repulsive fermionic Hubbard model. The doublon-hole condensate originates from an intrinsic doublon-hole exchange interaction and does not rely on the symmetry of the half-filled Hubbard model. It extends over a wide range of doublon densities and effective temperatures....
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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: Applied Physics Letters, 2020, vol. 117, no. 6, p. 062401
The binary compound V3Ga can exhibit two near-equilibrium phases, the A15 structure that is superconducting and the Heusler D03 structure that is semiconducting and antiferromagnetic. Density functional theory calculations show that these two phases are nearly degenerate, being separated in energy by only ±10 meV/atom. Our magnetization measurements on bulk-grown samples show ...
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In: Modern Physics Letters B, 2020, vol. 34, no. 19n20, p. 2040054
Ultrafast laser pulses can redistribute charges in Mott insulators on extremely short time scales, leading to the fast generation of photocarriers. It has recently been demonstrated that these photocarriers can form a novel η-paired condensate at low temperatures, featuring a staggered superconducting pairing field. In this conference paper, we discuss the origin of the η-paired hidden...
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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: 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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