Super-Poissonian Shot Noise of Squeezed-Magnon Mediated Spin Transport

摘要

The magnetization of a ferromagnet (F) driven out of equilibrium injects pure spin current into an adjacent conductor (N). Such F vertical bar N bilayers have become basic building blocks in a wide variety of spin-based devices. We evaluate the shot noise of the spin current traversing the F vertical bar N interface when F is subjected to a coherent microwave drive. We find that the noise spectrum is frequency independent up to the drive frequency, and increases linearly with frequency thereafter. The low frequency noise indicates super-Poissonian spin transfer, which results from quasiparticles with effective spin. (h) over bar = (h) over bar (1+delta). For typical ferromagnetic thin films, delta similar to 1 is related to the dipolar interaction-mediated squeezing of F eigenmodes.