Research Update: Antiferromagnet also pumps spins

Prof. Jiang Xiao and co-workers recently predicted that significant spin pumping is possible in antiferromagnet. The result has been recently published on Physical Review Letters [link]. 

Spin pumping in ferromagnet is very well known. However, the spin pumping in antiferromagnet is generally believed to be vanishing because of the two compensating sublattices. This simple thinking is actually wrong. In this paper, we argue that the spin pumping from the two compensating sublattice actually constructively enhance each other instead of cancelling. The reason is that, at antiferromagnet resonance, the magnetizations of the two sublattices are in fact precessing in the same direction (with a pi phase difference).

The spin pumping current by AFM written in terms of the net magnetization m and Neel order parameter n is:

Due to the very high resonance frequency (THz) of AFM dynamics, the AFM spin pumping current can be much larger than that of FM (GHz), assuming that both dynamics have similar precession cone angle.

© Center for Quantum Control 2013