Ran Cheng, Di Xiao, and Arne Brataas
https://journals.aps.org/prl/accepted/dc075Yb7W7212d55637e32c0607d5319623ad88bf
We consider the current-induced dynamics of insulating antiferromagnets in a spin Hall geometry. Sufficiently large in-plane currents perpendicular to the N\'{e}el order trigger spontaneous oscillations at frequencies between the acoustic and the optical eigenmodes. The direction of the driving current determines the chirality of the excitation. When the current exceeds a threshold, the combined effect of current-induced torques and spin pumping introduces a dynamic feedback that sustains steady-state oscillations with amplitudes controllable via the applied current. The AC voltage output is calculated numerically as a function of the DC current input for different feedback strengths. Our findings open a route towards Terahertz antiferromagnetic spin-torque oscillators.
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