Print Email Facebook Twitter Directional Excitation of a High-Density Magnon Gas Using Coherently Driven Spin Waves 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 gasNitrogen-vacancy centersScanning-probe magnetometrySpin relaxometrySpin wavesYttrium iron garnetHigh Tech Systems & MaterialsIndustrial Innovation To reference this document use: http://resolver.tudelft.nl/uuid:d2166a00-7289-47e2-80cf-536725671a2f 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 Files To receive the publication files, please send an e-mail request to TNO Library.