Large and Small Fermi-Surface Spin Density Waves in the Kondo Lattice Model

TL;DR

This paper reveals the existence of metallic spin density waves with varying Fermi surface sizes in the Kondo lattice model, showing how phase transitions depend on coupling strength and avoiding a local quantum critical point.

Contribution

It demonstrates the presence of SDWs with different Fermi surface sizes in the Kondo lattice model using real space dynamical mean field theory, detailing their phase transitions.

Findings

Fermi surface size changes from small to large with increasing coupling.

Second order transition from large Fermi-surface SDW to paramagnetic phase.

First order transition from small Fermi-surface SDW to paramagnetic phase.

Abstract

We demonstrate the existence of metallic spin density waves (SDWs) in the Kondo lattice model on a square lattice for a wide range of parameters by means of real space dynamical mean field theory. In these SDWs, the spin polarization as well as the charge density depend on the lattice site and are modulated along one direction of the square lattice. We show that within this phase of metallic SDWs the Fermi surface changes from small to large, when the coupling strength is increased. Furthermore, the transition between the large Fermi-surface SDW phase and the paramagnetic phase is of second order, while the transition between the small Fermi-surface SDW phase and the paramagnetic phase is of first order. A local quantum critical point is thus avoided in our calculations by undergoing a first order phase transition.