Kondo destruction in a quantum paramagnet with magnetic frustration

TL;DR

This study investigates how magnetic frustration influences Kondo destruction and Fermi surface changes in the heavy-fermion compound CePdAl, revealing a complex interplay between frustration, Kondo effect, and quantum criticality.

Contribution

It provides experimental evidence of a thermally broadened Fermi surface crossover line in a frustrated Kondo lattice, linking Kondo destruction with magnetic frustration.

Findings

Identification of a B*(T) line indicating a Fermi surface crossover.

Observation of a spin-liquid state characterized by Tp(B).

Absence of non-Fermi-liquid behavior near the quantum critical point.

Abstract

We report results of isothermal magnetotransport and susceptibility measurements at elevated magnetic fields B down to very low temperatures T on high-quality single crystals of the frustrated Kondo-lattice system CePdAl. They reveal a B*(T) line within the paramagnetic part of the phase diagram. This line denotes a thermally broadened 'small'-to-'large' Fermi surface crossover which substantially narrows upon cooling. At B_0* = B*(T=0) = (4.6 +/- 0.1) T, this B*(T) line merges with two other crossover lines, viz. Tp(B) below and T_FL(B) above B_0*. Tp characterizes a frustration-dominated spin-liquid state, while T_FL is the Fermi-liquid temperature associated with the lattice Kondo effect. Non-Fermi-liquid phenomena which are commonly observed near a 'Kondo destruction' quantum critical point cannot be resolved in CePdAl. Our observations reveal a rare case where Kondo coupling, frustration and quantum criticality are closely intertwined.