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

Phys Rev Lett. 2016 Apr 8;116(14):146601. doi: 10.1103/PhysRevLett.116.146601. Epub 2016 Apr 8.

Abstract

The magnetization of a ferromagnet (F) driven out of equilibrium injects pure spin current into an adjacent conductor (N). Such F|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|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 ℏ^{*}=ℏ(1+δ). For typical ferromagnetic thin films, δ∼1 is related to the dipolar interaction-mediated squeezing of F eigenmodes.

Publication types

  • Research Support, Non-U.S. Gov't