Magnon-phonon interactions in the spinel compound MnSc$_2$Se$_4$

TL;DR

This study explores the magnetic and magnetoelastic behavior of MnSc$_2$Se$_4$ single crystals at low temperatures, revealing magnon-phonon interactions through experimental measurements and a microscopic model based on linear spin-wave theory.

Contribution

It provides the first detailed analysis of magnon-phonon interactions in MnSc$_2$Se$_4$ using combined experimental and theoretical approaches.

Findings

Magnetization increases linearly with field up to 15 T.

Longitudinal acoustic mode softens in magnetic field.

Magnetoelastic effects are explained by exchange-striction coupling.

Abstract

We investigated the magnetic and magnetoelastic properties of MnSc$_2$Se$_4$ single crystals at low temperature under a magnetic field directed along the crystallographic [111] axis. The magnetization data at low temperature show a linear increase with magnetic field, until saturation is reached above 15 T. In ultrasound, a longitudinal acoustic mode shows a softening in field, which is absent for a transverse acoustic mode. We discuss these results using a microscopic model based on the framework of linear spin-wave theory. The magnetic and magnetoelastic data are qualitatively reproduced by considering magnon-phonon interactions arising from exchange-striction coupling between the crystal lattice and spin-wave fluctuations in the zero-temperature limit.