Regensburg 2016 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 19: Transport: Fluctuation and Noise
(Joint session of DY and TT organized by TT)

DY 19.1: Vortrag

Dienstag, 8. März 2016, 14:00–14:15, H23

Super-Poissonian shot noise of squeezed-magnon mediated spin transport — •Akashdeep Kamra and Wolfgang Belzig — Fachbereich Physik, Universität Konstanz, D-78457 Konstanz, Germany

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 understood in terms of dipolar interaction mediated squeezing of F eigenmodes, which results in quasi-particles with effective spin ℏ^* = ℏ (1 + δ). For experimentally relevant parameters, we estimate δ ≈ 0.4 for yttrium iron garnet and δ ≈ 3.0 for iron thin films. The spontaneous squeezing of F eigenmodes suggests novel possibilities for their applications in quantum optics and related fields.