Incommensurate crystal supercell and polarization-flop observed in the magnetoelectric ilmenite, MnTiO3

TL;DR

This study reveals a supercell and polarization-flop in MnTiO3, highlighting complex magnetoelectric interactions and the importance of local spin-lattice coupling in its behavior.

Contribution

It provides new evidence of a supercell structure and polarization-flop in MnTiO3, emphasizing the role of local spin-lattice interactions in its magnetoelectric properties.

Findings

Presence of a supercell breaking R-3 symmetry

Observation of polarization-flop at 6.5 T

Non-zero off-diagonal magnetoelectric tensor elements

Abstract

MnTiO3 has been studied for many decades, but it was only in the last few years that its strong magnetoelectric behavior had been observed. Here, we use neutron scattering on two separately grown single crystals and two powder samples to show the presence of a supercell that breaks R-3 symmetry. We also present the temperature and field dependence of the dielectric constant and pyroelectric current, and show evidence of non-zero off-diagonal magnetoelectric tensor elements (forbidden by R-3 symmetry) followed by a polarization flop accompanying the spin flop transition at {\mu}0HSF = 6.5 T. M\"ossbauer spectroscopy on MnTiO3 gently doped with 57Fe was used to help shed light on the impact of the supercell on the observed behavior. Although the full supercell structure could not be solved at this time due to a lack of visible reflections, the full-scope of the results presented here suggest that the role of local spin-lattice coupling in the magnetoelectric properties of MnTiO3 is likely more important than previously thought.