Nonlinear Néel Spin-Orbit Torque in Centrosymmetric Antiferromagnets

Abstract

Electric control of Néel vector is a central task of antiferromagnetic (AFM) spintronics. The major scheme so far relies on the linear Néel torque, which however is restricted to AFMs with broken inversion symmetry. Here, we propose a nonlinear Néel spin-orbit torque, uniquely enabling electric control in the vast class of centrosymmetric AFMs, where the existing scheme fails. Importantly, its intrinsic component, rooted in sublattice-resolved band quantum geometry, offers two additional advantages: It operates also in $\mathcal{P}\mathcal{T}$-symmetric AFM insulators, where linear torque is forbidden; and it has anti-damping character, making it more efficient in driving magnetic dynamics. Combined with first-principles calculations, we predict large effect in MnRh and MnBi${}_2$Te${}_4$, which can be readily detected in experiment. Our work unveils a new fundamental effect, offers a new strategy of electric control in AFM systems beyond the existing paradigm, and opens the door to the field of nonlinear AFM spintronics.

6 pages, 4 figures and 1 table