Title
Directional Excitation of a High-Density Magnon Gas Using Coherently Driven Spin Waves
Author
Simon, B.G.
Kurdi, S.
La, H.
Bertelli, I.
Carmiggelt, J.J.
Ruf, M.
de Jong, N.
van den Berg, H.
Katan, A.J.
van der Sar, T.
Publication year
2021
Abstract
Controlling magnon densities in magnetic materials enables driving spin transport in magnonic devices. We demonstrate the creation of large, out-of-equilibrium magnon densities in a thin-film magnetic insulator via microwave excitation of coherent spin waves and subsequent multimagnon scattering. We image both the coherent spin waves and the resulting incoherent magnon gas using scanning-probe magnetometry based on electron spins in diamond. We find that the gas extends unidirectionally over hundreds of micrometers from the excitation stripline. Surprisingly, the gas density far exceeds that expected for a boson system following a Bose–Einstein distribution with a maximum value of the chemical potential. We characterize the momentum distribution of the gas by measuring the nanoscale spatial decay of the magnetic stray fields. Our results show that driving coherent spin waves leads to a strong out-of-equilibrium occupation of the spin-wave band, opening new possibilities for controlling spin transport and magnetic dynamics in target directions.
Subject
Magnon gas
Nitrogen-vacancy centers
Scanning-probe magnetometry
Spin relaxometry
Spin waves
Yttrium iron garnet
High Tech Systems & Materials
Industrial Innovation
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DOI
https://doi.org/10.1021/acs.nanolett.1c02654
TNO identifier
967720
Publisher
American Chemical Society ACS
ISSN
1530-6984
Source
Nano Letters, 21 (21), 8213-8219
Document type
article