We present a comprehensive x-ray scattering study of spontaneous magnetostriction in hexagonal MnTe, an antiferromagnetic semiconductor with a Neel temperature of TN=307 K. We observe the largest spontaneous magnetovolume effect known for an antiferromagnet, reaching a volume contraction of ∣ΔV/V∣>7×10−3. This can be justified semiquantitatively by considering bulk material properties, the spatial dependence of the superexchange interaction, and the geometrical arrangement of magnetic moments in MnTe. The highly unusual linear scaling of the magnetovolume effect with the short-range magnetic correlations, beginning in the paramagnetic state well above TN, points to a novel physical mechanism, which we explain in terms of a trilinear coupling of the elastic strain with superposed distinct domains of the antiferromagnetic order parameter. This novel mechanism for coupling lattice strain to robust short-range magnetic order casts new light on magnetostrictive phenomena and also provides a template by which the exceptional magnetostrictive properties of MnTe might be realized in a wide range of other functional materials.
@article{arxiv.2305.17549,
title = {Giant spontaneous magnetostriction in MnTe driven by a novel magnetostructural coupling mechanism},
author = {Raju Baral and Milinda Abeykoon and Branton J. Campbell and Benjamin A. Frandsen},
journal= {arXiv preprint arXiv:2305.17549},
year = {2023}
}