Collective Dynamics of Coexisting Spin Textures

Advances in controlling electron correlations in transition metal dichalcogenides have opened a new frontier of many-body physics in two dimensions. A field where these materials have yet to make a deep impact is antiferromagnetic spintronics—a relatively new research direction promising technologies with fast switching times, insensitivity to magnetic perturbations and reduced cross-talk. The theory behind the electrical switching of antiferromagnets is premised on the existence of a well-defined broken symmetry state that can be rotated to encode information. A spin glass is in many ways the antithesis of this state, characterized by an ergodic landscape of nearly degenerate magnetic configurations, freezing into its final distribution in a manner that is seemingly bereft of information.

In this talk, I will show that the coexistence of spin glass and antiferromagnetic order allows a novel mechanism to facilitate the switching of the intercalated transition metal dichalcogenide Fe_1/3±δNbS₂, which is rooted in the electrically stimulated collective winding of the spin glass. We find that remarkably low current densities of the order of 10⁴ A/cm⁻² can reorient the magnetic order in a single pulse activation. The local texture of the spin glass opens an anisotropic channel of interaction that can be used to rotate the equilibrium spin-orientation of the antiferromagnetic state. Moreover, I will present the first experimental observation of the predicted spin glass collective modes, known as Halperin-Saslow spin waves. The use of a spin glass’ collective dynamics to electrically manipulate antiferromagnetic spin textures has never been applied before, opening the field of antiferromagnetic spintronics to many more material platforms with complex magnetic textures.