The spin glass-antiferromagnetism competition in Kondo-lattice systems in the presence of a transverse applied magnetic field

TL;DR

This paper develops a theoretical model to describe the complex interplay of antiferromagnetism, spin glass behavior, and Kondo effects in Kondo-lattice systems under a transverse magnetic field, matching experimental phase diagrams.

Contribution

It introduces a quantum theoretical framework using path integrals and the replica trick to analyze competing magnetic phases in Kondo-lattice systems with disorder and transverse field effects.

Findings

Phase diagram matches experimental sequence for Ce2Au1-xCoxSi3.

Qualitative agreement on freezing and Neel temperatures decreasing to a QCP.

Model captures the competition among AF, SG, and Kondo effects under transverse field.

Abstract

A theory is proposed to describe the competition among antiferromagnetism (AF), spin glass (SG) and Kondo effect. The model describes two Kondo sublattices with an intrasite Kondo interaction strength $J_{K}$ and a random Gaussian interlattice interaction in the presence of a transverse field $\Gamma$. The $\Gamma$ field is introduced as a quantum mechanism to produce spin flipping and the random coupling has average $-2J_0/N$ and variance $32 J^{2}/N$. The path integral formalism with Grassmann fields is used to study this fermionic problem, in which the disorder is treated within the framework of the replica trick. The free energy and the order parameters are obtained using the static ansatz. In this many parameters problem, we choose $J_0/J \approx (J_{K}/J)^{2}$ and $\Gamma/J \approx (J_{K}/J)^{2}$ to allow a better comparison with the experimental findings. The obtained phase diagram has not only the same sequence as the experimental one for $Ce_{2}Au_{1-x}Co_{x}Si_{3}$, but mainly, it also shows a qualitative agreement concerning the behavior of the freezing temperature and the Neel temperature which decreases until a Quantum Critical Point (QCP).