Spin Glass and Ferromagnetism in Kondo lattices compounds

TL;DR

This paper investigates the phase diagram of Kondo lattice compounds with random inter-site interactions, revealing multiple magnetic phases and their relation to experimental observations in CeNi_{1-x}Cu_x.

Contribution

It introduces a mean field analysis of the Kondo lattice with random interactions, identifying various magnetic and Kondo phases using a path integral approach.

Findings

Phase transitions among ferromagnetic, spin glass, mixed, and Kondo states.

Dependence of phases on interaction parameters Jo, J, and Jk.

Relevance to experimental data for CeNi_{1-x}Cu_x.

Abstract

The Kondo lattice model has been analyzed in the presence of a random inter-site interaction among localized spins with non zero mean Jo and standard deviation J. Following the same framework previously introduced by us, the problem is formulated in the path integral formalism where the spin operators are expressed as bilinear combinations of Grassmann fields. The static approximation and the replica symmetry ansatz have allowed us to solve the problem at a mean field level. The resulting phase diagram displays several phase transitions among a ferromagnetically ordered region,a spin glass one, a mixed phase and a Kondo state depending on Jo, J and its relation with the Kondo interaction coupling Jk. These results could be used to address part of the experimental data for the CeNi_{1-x}Cu_x compound, when x =< 0.8.