Evidence for a Non-Fermi-Liquid Phase in Ge-Substituted YbRh2Si2

TL;DR

This paper presents evidence that Ge-substituted YbRh2Si2 exhibits a non-Fermi-liquid phase over a finite temperature range, challenging the traditional view of a single quantum critical point in heavy fermion systems.

Contribution

It demonstrates the existence of a non-Fermi-liquid phase in Ge-substituted YbRh2Si2, suggesting a new class of metallic phase beyond the standard quantum critical point paradigm.

Findings

Non-Fermi-liquid behavior observed over a finite temperature range

Evidence suggests a new metallic phase, not due to disorder

Challenges the single quantum critical point model in heavy fermion systems

Abstract

The canonical view of heavy fermion quantum criticality assumes a single quantum critical point separating the paramagnet from the antiferromagnet. However, recent experiments on Yb-based heavy fermion compounds suggest the presence of non-Fermi liquid behavior over a finite zero-temperature region. Using detailed susceptibility and transport measurements we show that the classic quantum critical system, Ge-substituted YbRh2Si2, also displays such behavior. We advance arguments that this is not due to a disorder-smeared quantum critical point, but represents a new class of metallic phase.