Magnetostriction and magnetostructural domains in CoTiO$_3$

TL;DR

This study investigates magnetostrictive effects and domain behavior in CoTiO$_3$, revealing significant magnetoelastic coupling, anisotropic lattice deformation, and the influence of magnetic and structural domains across the antiferromagnetic transition.

Contribution

It provides detailed experimental insights into the magnetostrictive properties and domain dynamics of CoTiO$_3$, highlighting the role of multi-domain phenomena and magnetoelastic coupling.

Findings

Pronounced length changes indicating strong magnetoelastic coupling.

Anisotropic lattice deformation depending on magnetic field orientation.

Presence of magnetic and structural domains affecting magnetic response.

Abstract

We report the magnetostrictive length changes of CoTiO$_3$ studied by means of high-resolution dilatometry in magnetic fields ($B$) up to 15~T. In the long-range antiferromagnetically ordered phase below $T_N$ = 38~K, the easy-plane type spin structure undergoes a spin-reorientation transition in the $ab$ plane in magnetic fields $B || ab \approx 2$~T. We observe pronounced length changes driven by external magnetic field in this field region indicating significant magnetoelastic coupling in CoTiO$_3$. Specifically, we observe anisotropic deformation of the lattice for fields applied in the $ab$ plane. While, for $B \lesssim 2$~T, in-plane magnetostriction shows that the lattice expands (contracts) parallel (perpendicular) to the field direction, the opposite behaviour appear at higher fields. Furthermore, there are remarkable effects of slight changes in the applied uniaxial pressure on the magnetostrictive response of CoTiO$_3$ persisting to temperatures well above $T_N$. The data evidence the presence of magnetic domains below $T_N$ as well as of structural ones in CoTiO$_3$. The presence of magnetic domains in the spin ordered phase is further evidenced by an additional 3-fold magnetic anisotropy appearing below $T_N$. We discuss the effects of rotational magnetic domains on isothermal magnetization and magnetostriction and interpret our results on the basis of a multi-domain phenomenological model.