Dresden 2020 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 59: Correlated Electrons: Quantum Impurities and Kondo Physics; Other Materials

TT 59.1: Vortrag

Donnerstag, 19. März 2020, 15:00–15:15, HSZ 03

Phase Diagram and Dynamics of an SU( N) Symmetric Kondo Lattice Model — •Marcin Raczkowski and Fakher Assaad — Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany

We study the interplay between Kondo screening and the magnetic RKKY interaction in an SU(N) symmetric generalization of the two-dimensional half-filled Kondo lattice model (KLM) by quantum Monte Carlo simulations with N up to 8 [1]. While the long-range antiferromagnetic (AF) order in SU(N) quantum spin systems typically gives way to spin-singlet ground states with spontaneously broken lattice symmetry, we find that the SU(N) KLM in the totally antisymmetric self-adjoint representation is unique in that for each finite N its ground-state phase diagram hosts only two phases – AF order and the Kondo-screened phase. We believe that it is the enhanced range of the RKKY interaction that is the key to stabilize antiferromagnetism at large N. Given that the range of the RKKY interaction grows as a function of N, we generically expect that the relevant physics will become more mean-field-like. A resolved abrupt jump of the coherence temperature across the phase transition for N>2 supports this line of arguing and sheds new light on the rapid loss of coherence at the magnetic phase transition in heavy-fermion systems.

[1] M. Raczkowski and F. F. Assaad, arXiv:1910.07540 (2019).

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