Quadrupole-Driven Non-Fermi Liquid and Magnetic-Field Induced Heavy Fermion States in a Non-Kramers Doublet System

TL;DR

This paper reports the discovery of non-Fermi liquid behavior and magnetic-field-induced heavy fermion states in a non-Kramers doublet system with quadrupolar degrees of freedom, highlighting a novel quadrupole Kondo lattice formation.

Contribution

It presents the first observation of NFL behavior in a purely quadrupole-active system, suggesting a new type of quadrupole Kondo lattice driven by quadrupolar conduction electron hybridization.

Findings

Observation of NFL behavior in resistivity and specific heat above TQ

Scaling of data with characteristic temperatures T0 in magnetic fields below 6 T

Field-induced crossover to Fermi-liquid state near 5 T

Abstract

Orbital degrees of freedom in condensed matters could play important roles in forming a variety of exotic electronic states by interacting with conduction electrons. In 4f electron systems, because of strong intra-atomic spin-orbit coupling, an orbitally degenerate state inherently carries quadrupolar degrees of freedom. The present work has focussed on a purely quadrupole-active system PrIr2Zn20 showing superconductivity in the presence of an antiferroquadrupole order at TQ = 0.11 K. We observed non-Fermi liquid (NFL) behaviors emerging in the electrical resistivity and the 4f contribution to the specific heat, C_4f, in the paramagnetic state at T > TQ. Moreover, in magnetic fields below 6 T, all data set of the electrical resistivity and C_4f(T) are well scaled with characteristic temperatures T0's. This is the first observation of the NFL state in the nonmagnetic quadrupole-active system, whose origin is intrinsically different from that observed in the vicinity of the conventional quantum critical point. It implies possible formation of a quadrupole Kondo lattice resulting from hybridization between the quadrupoles and the conduction electrons. Below 0.13 K, the electrical resistivity and C_4f(T) exhibit anomalies as B approaches 5 T. This is the manifestation of a field-induced crossover toward a Fermi-liquid ground state in the quadrupole Kondo lattice.