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TT: Fachverband Tiefe Temperaturen

TT 43: Poster: Correlated Electrons II

TT 43.29: Poster

Wednesday, March 29, 2023, 15:00–18:00, P2/OG3

Spectral densities of quantum magnets with quenched disorder using the coherent potential approximation and perturbative continuous unitary transformations — •Max Hörmann and Kai Phillip Schmidt — Institut für Theoretische Physik I, Universität Erlangen-Nürnberg, Staudtstraße 7, 91058 Erlangen

We combine perturbation theory by means of perturbative continuous transformations together with the coherent potential approximation to derive approximations for the averaged spectral density of the antiferromagnetic dimer-diluted Heisenberg bilayer model and the spin-diluted transverse-field Ising model on the square latttice. To this end, we calculate a dilution dependent series for the real and imaginary part of the one quasi-particle self-energy. While the real part shifts the extremal energy of the spectral density for fixed momentum the imaginary part reflects the finite-lifetime of momentum modes. Using extrapolations we study the applicability of this approach to critical behaviour and derive approximations for averaged spectral densities in non-perturbative regimes.