Quadrupolar Kondo Effect in Non-Kramers Doublet System PrInAg2

TL;DR

This study investigates the quadrupolar Kondo effect in PrInAg_2 through ultrasonic measurements, revealing characteristic elastic constant behavior and evidence of quadrupolar moment quenching at very low temperatures.

Contribution

It provides experimental evidence of the quadrupolar Kondo effect in a non-Kramers doublet system using ultrasonic techniques, highlighting the behavior of elastic constants at low temperatures.

Findings

Elastic constant (c_{11}-c_{12})/2 softens below 10 K due to quadrupolar susceptibility.

(c_{11}-c_{12})/2 shows -lnT dependence below 0.1 K, indicating quadrupolar Kondo state.

Magnetic field effects align with quadrupolar susceptibility models for the 4f^2 state.

Abstract

We performed ultrasonic measurement on the rare-earth intermetallic compound PrInAg_2 to examine the quadrupolar Kondo effect associated with the non-Kramers Gamma_3 doublet ground state. The characteristic softening of the elastic constant (c_{11}-c_{12})/2 below 10 K in PrInAg_2 is attributed to a Curie term in quadrupolar susceptibility for the quadrupole O_2^2=J_x^2-J_y^2 of the stable Gamma_3 ground state. (c_{11}-c_{12})/2 turns to a slight increase with the -lnT dependence below 0.1 K, which suggests the quenching of the quadrupolar moment in the quadrupolar Kondo state. Under applied magnetic fields of 10 T and 15 T above 8.7 T corresponding to the Kondo temperature T_K of ~ 0.86 K, the behavior of (c_{11}-c_{12})/2 is described in terms of quadrupolar susceptibility for the stable 4f^2 state.