Spin-torque–driven antiferromagnetic resonance

Abstract

The intrinsic fast dynamics make antiferromagnetic spintronics a promising avenue for faster data processing. Ultrafast antiferromagnetic resonance–generated spin current provides valuable access to antiferromagnetic spin dynamics. However, the inverse effect, spin-torque–driven antiferromagnetic resonance (ST-AFMR), which is attractive for practical utilization of fast devices but seriously impeded by difficulties in controlling and detecting Néel vectors, remains elusive. We observe ST-AFMR in Y 3 Fe 5 O 12 /α-Fe 2 O 3 /Pt at room temperature. The Néel vector oscillates and contributes to voltage signal owing to antiferromagnetic negative spin Hall magnetoresistance–induced spin rectification effect, which has the opposite sign to ferromagnets. The Néel vector in antiferromagnetic α-Fe 2 O 3 is strongly coupled to the magnetization in Y 3 Fe 5 O 12 buffer, resulting in the convenient control of Néel vectors. ST-AFMR experiment is bolstered by micromagnetic simulations, where both the Néel vector and the canted moment of α-Fe 2 O 3 are in elliptic resonance. These findings shed light on the spin current–induced dynamics in antiferromagnets and represent a step toward electrically controlled antiferromagnetic terahertz emitters.