Spin-lattice coupling in a ferrimagnetic spinel: The exotic $H$-$T$ phase diagram of MnCr$_2$S$_4$ up to 110 T

TL;DR

This study reveals the crucial role of spin-lattice coupling in ferrimagnetic spinels, demonstrating complex high-field phase diagrams and novel phase transitions in MnCr₂S₄ through ultrahigh-field measurements and theoretical modeling.

Contribution

It shows that spin-lattice coupling is essential in ferrimagnetic spinels and introduces a minimal model that explains complex high-field phases and transitions.

Findings

Identification of two new high-field phase transitions at 75 and 85 T.

Observation of a robust magnetization plateau between unconventional phases.

Confirmation that spin-lattice coupling significantly influences ferrimagnetic spinel behavior.

Abstract

In antiferromagnets, the interplay of spin frustration and spin-lattice coupling has been extensively studied as the source of complex spin patterns and exotic magnetism. Here, we demonstrate that, although neglected in the past, the spin-lattice coupling is essential to ferrimagnetic spinels as well. We performed ultrahigh-field magnetization measurements up to 110 T on a Yafet-Kittel ferrimagnetic spinel, MnCr$_2$S$_4$, which was complemented by measurements of magnetostriction and sound velocities up to 60 T. Classical Monte Carlo calculations were performed to identify the complex high-field spin structures. Our minimal model incorporating spin-lattice coupling accounts for the experimental results and corroborates the complete phase diagram, including two new high-field phase transitions at 75 and 85 T. Magnetoelastic coupling induces striking effects: An extremely robust magnetization plateau is embedded between two unconventional spin-asymmetric phases. Ferrimagnetic spinels provide a new platform to study asymmetric and multiferroic phases stabilized by spin-lattice coupling.