Non-Fermi Liquid Behavior Close to a Quantum Critical Point in a Ferromagnetic State without Local Moments

E Svanidze,L Liu,T J S Munsie,T Besara,T Siegrist,M B Maple,B D White,B Frandsen,Y J Uemura,G M Luke,C Q Jin,T Medina,E Morosan,D Zheng,T Goko

doi:10.1103/physrevx.5.011026

Abstract

A quantum critical point (QCP) occurs upon chemical doping of the weak itinerant ferromagnet Sc_{3.1}In. Remarkable for a system with no local moments, the QCP is accompanied by non-Fermi liquid (NFL) behavior, manifested in the logarithmic divergence of the specific heat both in the ferro- and the paramagnetic states. Sc_{3.1}In displays critical scaling and NFL behavior in the ferromagnetic state, akin to what had been observed only in f-electron, local moment systems. With doping, critical scaling is observed close to the QCP, as the critical exponents, and delta, gamma and beta have weak composition dependence, with delta nearly twice, and beta almost half of their respective mean-field values. The unusually large paramagnetic moment mu_PM~1.3 mu_B/F.U. is nearly composition-independent. Evidence for strong spin fluctuations, accompanying the QCP at x_c = 0.035 +- 0.005, may be ascribed to the reduced dimensionality of Sc_{3.1}In, associated with the nearly one-dimensional Sc-In chains.

Highlights

Quantum critical points (QCPs) are ubiquitous features in the phase diagrams of strongly correlated electron systems, ranging from high-temperature oxide superconductors [1,2,3] and low-dimensional compounds [4,5,6], to itinerant magnets (IMs) [7,8,9,10] and heavy fermions (HFs) [11,12,13,14,15,16]
Remarkable for a system with no local moments, the QCP is accompanied by non-Fermi liquid behavior, manifested in the logarithmic divergence of the specific heat both in the ferro-and the paramagnetic states, as well as linear temperature dependence of the low-temperature resistivity
Non-Fermi liquid (NFL) behavior [17,18,19,20,21], and critical scaling [22] accompany the QCP, and such novel phenomena have been extensively studied in HFs and, in particular, in antiferromagnetically ordered systems

Summary

Introduction

Quantum critical points (QCPs) are ubiquitous features in the phase diagrams of strongly correlated electron systems, ranging from high-temperature oxide superconductors [1,2,3] and low-dimensional compounds [4,5,6], to itinerant magnets (IMs) [7,8,9,10] and heavy fermions (HFs) [11,12,13,14,15,16]. Non-Fermi liquid (NFL) behavior [17,18,19,20,21], and critical scaling [22] accompany the QCP, and such novel phenomena have been extensively studied in HFs and, in particular, in antiferromagnetically ordered systems.

Methods

Results

Conclusion