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MA: Fachverband Magnetismus

MA 59: Posters Magnetism III

MA 59.42: Poster

Freitag, 20. März 2020, 09:00–12:00, P2/EG

Phase diagram and linearized dynamics of the classical-spin Kondo model on the triangular lattice — •Michael Lau and Michael Potthoff — I. Institute of Theoretical Physics, Department of Physics, Universität Hamburg

We study the ground-state phase diagram and the linearized real-time dynamics of the Kondo model with classical spins on the half-filled magnetically frustrated two-dimensional triangular lattice. The phase diagram is obtained via a novel technique using an (unphysical) Gilbert damping term to approach the ground state by solving the coupled equations of motion for the classical spins and the reduced one-particle density matrix of the conduction-electron system with a high-order Runge-Kutta method.

We find the classical noncollinear 120^∘ phase in the regime of strong Kondo coupling J as reflected in the spin-structure factor for the classical as well as for the quantum spin-spin correlations by strong peaks at the K-points. At intermediate J, there is a first-order phase transition to a collinear zigzag phase, which exhibits a threefold rotational degeneracy as is again nicely reflected in the spin-structure factor.

The phase diagram sets the stage for subsequent analytical and numerical studies of the real-time dynamics. We compare the full solution of the (physical) equations of motion with the linearized variant in the limit of small excitation energies and study the dispersions of the Goldstone modes and the linearized dynamics close to the critical point.