Magnetic and multiferroic phases of single-crystalline Mn$_{0.85}$Co$_{0.15}$WO$_4$

TL;DR

This study explores the complex magnetic and multiferroic phase diagram of Mn$_{0.85}$Co$_{0.15}$WO$_4$ single crystals, revealing multiple magnetic phases and their relation to ferroelectric polarization.

Contribution

It provides detailed experimental characterization of magnetic structures and phase transitions in Mn$_{0.85}$Co$_{0.15}$WO$_4$, highlighting the coexistence of multiple magnetic phases and their impact on ferroelectricity.

Findings

Identification of three magnetic phase transitions.

Observation of ferroelectric polarization only along the b-axis below 10 K.

Detection of up to four coexisting magnetic structures.

Abstract

The magnetic and multiferroic phase diagram of Mn$_{0.85}$Co$_{0.15}$WO$_4$ single crystals is investigated by means of magnetic, heat capacity, dielectric, polarization, and neutron scattering experiments. Three magnetic phase transitions are detected through distinct anomalies in all physical quantities. The ferroelectric polarization is observed only along the b-axis below 10 K but not along the a-axis as recently suggested. The magnetic phases studied by neutron scattering are very complex. Up to four different magnetic structures, partially coexisting at certain temperature ranges, have been identified. Upon decreasing temperature two commensurate phases (AF4, AF1) are followed by an incommensurate phase (AF5) and a second incommensurate phase (AF2) is detected as a minor phase. The ferroelectric polarization is possibly associated with both (AF2 and AF5) phases.