Field-Induced Quantum Critical Point in CeCoIn5

TL;DR

This study investigates the suppression of non-Fermi liquid behavior and the emergence of a Fermi liquid state in CeCoIn5 under magnetic fields, revealing a field-induced quantum critical point coinciding with the superconducting critical field.

Contribution

It provides experimental evidence for a field-induced quantum critical point in CeCoIn5, linking magnetic field effects to quantum criticality and superconductivity.

Findings

Suppression of non-Fermi liquid behavior with increasing magnetic field

Observation of a Fermi liquid state characterized by T^2 resistivity dependence

Critical behavior of the T^2 coefficient with an exponent of 1.37

Abstract

The resistivity of the heavy-fermion superconductor CeCoIn5 was measured as a function of temperature, down to 25 mK and in magnetic fields of up to 16 T applied perpendicular to the basal plane. With increasing field, we observe a suppression of the non-Fermi liquid behavior, rho ~ T, and the development of a Fermi liquid state, with its characteristic rho = rho_0 + AT^2 dependence. The field dependence of the T^2 coefficient shows critical behavior with an exponent of 1.37. This is evidence for a field-induced quantum critical point (QCP), occuring at a critical field which coincides, within experimental accuracy, with the superconducting critical field H_c2. We discuss the relation of this field-tuned QCP to a change in the magnetic state, seen as a change in magnetoresistance from positive to negative, at a crossover line that has a common border with the superconducting region below ~ 1 K.