Past Events

Abstract

It has been known that spin current can exert a torque, known as the spin-transfer torque, on the ferromagnetic order parameter - magnetization and induce magnetization dynamics. Reciprocally, the magnetization dynamics can pump pure spin current into normal metals contacts, known as spin pumping. It has been generally believed that spin pumping in antiferromagnetic materials vanishes due to the two compensating sublattices. In this talk, I will show that, counter intuitively, the spin pumping from the two sublattices in constructively add up rather than cancel. By adopting a simple tight binding model for cubic antiferromagnet insulators, we derive pumped spin and staggered spin currents in terms of the staggered field, the magnetization, and their rates of change. For both compensated and uncompensated interfaces, spin pumping is of a similar magnitude as in ferromagnets with a direction controlled by the polarization of the driving microwave. The pumped currents are connected to current-induced torques via Onsager reciprocity relations. The spin pumping and spin-transfer torque in antiferromagnet open a new window towards THz information processing based on antiferromagnet.

Coffee and tea will be served 20 minutes prior to the seminar.