Nonlocal Spin Transport as a Probe of Viscous Magnon Fluids
Abstract
Magnons in ferromagnets behave as a viscous fluid over a length scale, the momentum-relaxation length, below which momentum-conserving scattering processes dominate. We show theoretically that in this hydrodynamic regime viscous effects lead to a sign change in the magnon chemical potential, which can be detected as a sign change in the nonlocal resistance measured in spin transport experiments. This sign change is observable when the injector-detector distance becomes comparable to the momentum-relaxation length. Taking into account momentum- and spin-relaxation processes, we consider the quasiconservation laws for momentum and spin in a magnon fluid. The resulting equations are solved for nonlocal spin transport devices in which spin is injected and detected via metallic leads. Because of the finite viscosity we also find a backflow of magnons close to the injector lead. Our work shows that nonlocal magnon spin transport devices are an attractive platform to develop and study magnon-fluid dynamics.
Keywords
Cite
@article{arxiv.1903.02790,
title = {Nonlocal Spin Transport as a Probe of Viscous Magnon Fluids},
author = {Camilo Ulloa and A. Tomadin and J. Shan and M. Polini and B. J. van Wees and R. A. Duine},
journal= {arXiv preprint arXiv:1903.02790},
year = {2019}
}