Entropy evolution in the magnetic phases of partially frustrated CePdAl

TL;DR

This study investigates how magnetic fields influence the entropy and frustration in CePdAl, revealing conditions that may favor the emergence of a quantum spin liquid state in a heavy-fermion system.

Contribution

It introduces a new entropy-based frustration parameter and explores the magnetic phase diagram under field suppression of the Kondo effect in CePdAl.

Findings

Magnetic field suppresses Kondo screening and enhances magnetic entropy.

Field range identified as promising for quantum spin liquid search.

Entropy-based frustration parameter correlates with magnetic phases.

Abstract

In the heavy-fermion metal CePdAl long-range antiferromagnetic order coexists with geometric frustration of one third of the Ce moments. At low temperatures the Kondo effect tends to screen the frustrated moments. We use magnetic fields $B$ to suppress the Kondo screening and study the magnetic phase diagram and the evolution of the entropy with $B$ employing thermodynamic probes. We estimate the frustration by introducing a definition of the frustration parameter based on the enhanced entropy, a fundamental feature of frustrated systems. In the field range where the Kondo screening is suppressed the liberated moments tend to maximize the magnetic entropy and strongly enhance the frustration. Based on our experiments, this field range may be a promising candidate to search for a quantum spin liquid.