Excitation spectra of the two dimensional Kondo insulator

Abstract

We present a Quantum Monte Carlo study of the temperature dependent dynamics of the two-dimensional Kondo insulator. Working at the so-called symmetrical point allows to perform minus-sign free QMC simulations. Study of the temperature dependence of the single-particle Green's function and the dynamical spin correlation function provides evidence for two characteristic temperatures, which we associate with the Kondo and coherence temperature, whereby the system shows a metal-insulator transition at the coherence temperature. The data shows evidence for two distinct types of spin excitations and we show that despite strong antiferromagnetic ordering at low temperature the system cannot be described by spin-density-wave theory.