バルクマグノン流雑音

Magnonic spin current-noise in insulating bulk magnets

仲田 光樹   ; 大沼 悠一*; 松尾 衛*

Nakata, Koki; Onuma, Yuichi*; Matsuo, Mamoru*

Keldysh形式(Green関数法)を用い、Fermi粒子系(電子系)に対する「Boltzmann-Langevinアプローチ」をBose粒子系(マグノン系)に発展・適用させ、量子統計性に依らない普遍的輸送物性をショットノイズ(非平衡雑音)の観点から明らかにする。

Extending a Boltzmann-Langevin theory to magnons, we show a universality of current-noise suppression in diffusive systems against the difference of quantum-statistical properties of bosons and fermions. We theoretically discover that compared with a Poissonian shot noise of magnons in an insulating ferromagnetic junction, the magnonic shot noise is suppressed in the diffusive insulating bulk magnet and noise-to-current ratio (Fano factor) at low temperatures exhibits a universal behavior, i.e., the same suppression 1/3 as the one for electron transport in diffusive conductors, despite the difference of quantum-statistical properties.