Spin Glass and antiferromagnetism in Kondo lattice disordered systems

TL;DR

This paper investigates the interplay of spin glass, antiferromagnetism, and Kondo effects in a disordered two-sublattice model, revealing a phase sequence consistent with experimental observations.

Contribution

It introduces a model with Gaussian-distributed inter-sublattice interactions and analyzes the phase diagram using mean field and replica symmetry methods.

Findings

Sequence of phases: spin glass, antiferromagnetism, then Kondo state

Qualitative agreement with experimental data on Ce_{2}Au_{1-x}Co_{x}Si_{3}

Phase transitions depend on increasing Kondo coupling

Abstract

The competition between spin glass (SG), antiferromagnetism (AF) and Kondo effect is studied here in a model which consists of two Kondo sublattices with a gaussian random interaction between spins in differents sublattices with an antiferromagnetic mean Jo and standard deviation J. In the present approach there is no hopping of the conduction electrons between the sublattices and only spins in different sublattices can interact. The problem is formulated in the path integral formalism where the spin operators are expressed as bilinear combinations of Grassmann fields which can be solved at mean field level within the static approximation and the replica symmetry ansatz. The obtained phase diagram shows the sequence of phases SG, AF and Kondo state for increasing Kondo coupling. This sequence agrees qualitatively with experimental data of the Ce_{2} Au_{1-x} Co_{x} Si_{3} compound.