Controllable emergent spatial spin modulation in Sr2IrO4 by in situ shear strain

TL;DR

This paper demonstrates that applying in situ shear strain to Sr2IrO4 induces a controllable, spatially modulated spin state due to competing anisotropic interactions, revealing a new route to exotic magnetic phases.

Contribution

It introduces a novel mechanism of strain-activated competing anisotropic interactions leading to tunable spin modulations in low-dimensional magnets.

Findings

Observation of a 12-layer spatial spin modulation under shear strain

Identification of a strain-induced anisotropic interaction at the 4th order

Demonstration of a controllable, symmetry-breaking magnetic phase

Abstract

Symmetric anisotropic interaction can be ferromagnetic and antiferromagnetic at the same time but for different crystallographic axes. We show that inducing competition of anisotropic interactions of orthogonal irreducible representations represents a general route to obtain new exotic magnetic states. We demonstrate it here by observing the emergence of a continuously tunable 12-layer spatial spin modulation when distorting the square lattice planes in the quasi-2D antiferromagnetic Sr2IrO4 under in situ shear strain. This translation-symmetry-breaking phase is a result of an unusual strain activated anisotropic interaction which is at the 4th order and competing with the inherent quadratic anisotropic interaction. Such a mechanism of competing anisotropy is distinct from that among the ferromagnetic, antiferromagnetic, and/or the Dzyaloshinskii-Moriya interactions, and it could be widely applicable and highly controllable in low dimensional magnets.