We observe that an rf microwave field strongly influences the transport of incoherent thermal magnons in yttrium iron garnet. Ferromagnetic resonance in the nonlinear regime suppresses thermal magnon transport by 95%. The transport is also modulated at non-resonant conditions in two cases, both related to the magnon band minimum. Firstly, a strong enhancement of the nonlocal signal appears at a static magnetic field below the resonance condition. This increase only occurs at one field polarity and can be as large as 800%. We attribute this effect to magnon kinetic processes, which give rise to band-minimum magnons and high-energy chiral surface modes. Secondly, the signal increases at a static field above the resonance condition, where the rf frequency coincides with the magnon band minimum. Our study gives insight into the interplay between coherent and incoherent spin dynamics: The rf field modifies the occupation of relevant magnon states and, via kinetic processes, the magnon spin transport.
@article{arxiv.1810.11667,
title = {Microwave control of thermal magnon spin transport},
author = {Jing Liu and Frank Feringa and Benedetta Flebus and Ludo J. Cornelissen and Johannes C. Leutenantsmeyer and Rembert A. Duine and Bart J. van Wees},
journal= {arXiv preprint arXiv:1810.11667},
year = {2019}
}