Universal $1/3$-suppression of magnonic shot noise in diffusive insulating magnets
Abstract
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. To this end, starting from a quantum kinetic equation for magnons subjected to thermal gradient in dilute impurities, we derive a bosonic counterpart of the semiclassical Boltzmann-Langevin equation for electrons and evaluate a magnonic current-noise in the diffusive insulating magnet. 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 as the one for electron transport in diffusive conductors, despite the difference of quantum-statistical properties. Finally, we show that our predictions are within experimental reach with current device and measurement technologies.
Keywords
Cite
@article{arxiv.1904.01151,
title = {Universal $1/3$-suppression of magnonic shot noise in diffusive insulating magnets},
author = {Kouki Nakata and Yuichi Ohnuma and Mamoru Matsuo},
journal= {arXiv preprint arXiv:1904.01151},
year = {2019}
}
Comments
4+4 pages; the title has been changed following the suggestion from the publisher