Berlin 2018 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 72: Poster Session: Correlated Electrons

TT 72.46: Poster

Mittwoch, 14. März 2018, 15:00–19:00, Poster B

Frustrated magnetism in the Kondo lattice on a zig-zag ladder — •Lena Woelk, Matthias Peschke, and Michael Potthoff — I. Institut für Theoretische Physik

We study the magnetic phase diagram of the Kondo lattice model on the half-filled zig-zag chain as a function of the exchange coupling J and the hopping amplitudes t,t′ in both the classical-spin and the quantum-spin case using a quantum-classical hybrid approach and the density matrix renormalization group (DMRG).

The competition between RKKY, superexchange, and the geometric frustration yields a complex phase diagram: We find multiple spiral phases, an antiferromagnetic phase as well as a small ferromagnetic region. In both the classical- and the quantum-spin case, we also find an extended region with a dimerized ground state, which consists of alternating ferro- and antiferromagnetic spin correlations along the rungs of the ladder. This alleviates the geometric frustration and is a precursor of quasi-long-range magnetic order.

The strong coupling limit J≫ t can be described with perturbation theory. The spin correlations in both the classical- and the quantum-spin case are captured by an effective classical Heisenberg model. In the weak coupling limit one expects the spin correlations to be governed by RKKY theory, this is checked against our results.