Effects of magnetic field and twin domains on magnetostructural phase mixture in Mn3O4: Raman scattering studies of untwinned crystals

TL;DR

This study uses Raman scattering to investigate how magnetic fields and twin domains influence the coexistence of magnetostructural phases in Mn3O4 crystals, revealing the effects of strain and intrinsic phase mixtures.

Contribution

It provides the first detailed Raman analysis of untwinned Mn3O4 crystals, clarifying the intrinsic phase behavior and the impact of twin domains on magnetic responses.

Findings

Distinct magnetic and vibrational spectra for each phase

Magnetostructural phase mixture responds to magnetic fields

Twin domains significantly influence phase coexistence

Abstract

The ferrimagnetic spinel Mn3O4 exhibits large and anisotropic changes in electronic and structural properties in response to an applied magnetic field. These changes are thought to result from the field-dependent tuning---via strong spin-lattice coupling---between two nearly degenerate magnetostructural phases. Recent variable-magnetic-field studies of Mn3O4 have been performed on melt-grown crystals, which can exhibit twin domains due to a Jahn-Teller structural transition below the melting temperature. Because of the near degeneracy of the magnetostructural phases, however, strain associated with the twin domains likely affects the magnetic responses of Mn3O4. In this report, we present a variable-magnetic-field Raman scattering study of untwinned Mn3O4 crystals grown out of a flux below the Jahn-Teller structural transition. We measure distinct q = 0 magnetic and vibrational excitation spectra for each isolated magnetostructural phase of untwinned Mn3O4 crystals and determine the symmetries of the observed excitations. We determine how the magnetostructural phase mixture changes in response to magnetic fields applied in the magnetic easy plane. Lastly, by comparing results on flux- and melt-grown Mn3O4 crystals, we show that the intrinsic mixture of the two magnetostructural phases is indeed strongly influenced by the presence of twin domains.