Interplay of Spin and Lattice Degrees of Freedom in the Frustrated Antiferromagnet CdCr_2O_4: High-field and Temperature Induced Anomalies of the Elastic Constants

TL;DR

This study investigates how spin and lattice interactions in the frustrated antiferromagnet CdCr_2O_4 cause anomalies in elastic constants under varying temperature and magnetic fields, highlighting strong spin-phonon coupling effects.

Contribution

It provides a detailed experimental analysis of spin-phonon coupling in CdCr_2O_4 and estimates the magneto-elastic interaction strength using theoretical comparison.

Findings

Strong spin-phonon coupling observed

Magneto-elastic interaction strength estimated

Anomalies linked to magnetic field and temperature variations

Abstract

Temperature and magnetic field studies of the elastic constants of the chromium spinel CdCr_2O_4 show pronounced anomalies related to strong spin-phonon coupling in this frustrated antiferromagnet. A detailed comparison of the longitudinal acoustic mode propagating along the [111] direction with theory based on an exchange-striction mechanism leads to an estimate of the strength of the magneto-elastic interaction. The derived spin-phonon coupling constant is in good agreement with previous determinations based on infrared absorption. Further insight is gained from intermediate and high magnetic field experiments in the field regime of the magnetization plateau. The role of the antisymmetric Dzyaloshinskii-Moriya interaction discussed and we compare the spin-phonon coupling in CdCr_2O_4 in both the ordered and disordered states.