Shape-induced phenomena in the finite size antiferromagnets

TL;DR

This paper demonstrates that the shape of finite-size antiferromagnetic samples influences their magnetic anisotropy through magnetoelastic effects, similar to ferromagnets, affecting domain structure and magnetic properties.

Contribution

It reveals that shape-induced phenomena in antiferromagnets arise from magnetoelastic coupling, leading to shape-dependent anisotropy and domain formation, extending ferromagnetic shape effects to antiferromagnets.

Findings

Shape controls antiferromagnetic anisotropy via magnetoelastic effects.

Shape-induced anisotropy can be enhanced in nanopillars due to lattice mismatch.

Effects are detectable through magnetic torque and resonance measurements.

Abstract

It is of common knowledge that the direction of easy axis in the finite-size ferromagnetic sample is controlled by its shape. In the present paper we show that a similar phenomenon should be observed in the compensated antiferromagnets with strong magnetoelastic coupling. Destressing energy which originates from the long-range magnetoelastic forces is analogous to demagnetization energy in ferromagnetic materials and is responsible for the formation of equilibrium domain structure and anisotropy of macroscopic magnetic properties. In particular, crystal shape may be a source of additional uniaxial magnetic anisotropy which removes degeneracy of antiferromagnetic vector or artificial 4th order anisotropy in the case of a square cross-section sample. In a special case of antiferromagnetic nanopillars shape-induced anisotropy can be substantially enhanced due to lattice mismatch with the substrate. These effects can be detected by the magnetic rotational torque and antiferromagnetic resonance measurements.