Coexistance of non-Fermi liquid behavior and bi-quadratic exchange coupling in La-substituted CeGe: Non-linear susceptibility and DFT + DMFT study

TL;DR

This study combines experimental and theoretical approaches to investigate non-Fermi liquid behavior and bi-quadratic exchange coupling in La-substituted CeGe, revealing the role of magnetic fluctuations and non-linear susceptibility scaling.

Contribution

It provides a detailed DFT+DMFT analysis of Ce0.24La0.76Ge, demonstrating NFL behavior linked to local moment fluctuations and identifying bi-quadratic exchange coupling as a key factor.

Findings

NFL behavior associated with fluctuating local moments

Bi-quadratic exchange coupling develops during the NFL to new phase transition

Magnetic fluctuations underlie the bi-quadratic exchange interaction

Abstract

Studies connected with the investigations of non-Fermi liquid (NFL) systems continue to attract interest in condensed matter physics community. Understanding the anomalous physical properties exhibited by such systems and its related electronic structures is one of the central research topics in this area. In this context, Ce-based and Ce-site diluted (with non-magnetic ions) compounds provide a fertile playground. Here, we present a detailed study of non-linear DC susceptibility and combined density functional theory plus dynamical mean field theory (DFT+DMFT) on Ce0.24La0.76Ge. Theoretical investigation of 4f partial density of states, local susceptibility and self-energy demonstrates the presence of NFL behavior which is associated with fluctuating local moments. Non-linear DC susceptibility studies on this compound reveal that the transition from NFL state to the new phase is due to development of the bi-quadratic exchange coupling and it obeys the non-linear susceptibility scaling. Under the application of magnetic fields, local moments interact spatially through conduction electrons resulting in magnetic fluctuations. Our studies point to the fact that the origin of the observed bi-quadratic exchange coupling is due to the spatial magnetic fluctuations.