Probing thermal magnon current mediated by coherent magnon via nitrogen-vacancy centers in diamond

The study of the interplay between heat currents and spins, spin caloritronics, has been intensively investigated recently owing to its potential in creating more efficient computing devices and versatile thermoelectric conversion technologies¹. We report the detection of thermal magnon current propagating in a magnetic insulator yttrium iron garnet under a temperature gradient, using electron spins hosted in a diamond matrix with nitrogen-vacancy (NV) defect centers. We exploit the interplay between coherent and incoherent magnons² to bridge the energy mismatch between thermal magnon current and NV spin. The thermal magnon current emanates as a change in Rabi oscillation frequencies as well as longitudinal relaxation rates of the NV spins³. The ability to locally probe thermal magnon current can serve as a basis for creating a new device platform hybridizing spin caloritronics and spin qubits.

References:
1. G. E. W. Bauer, E. Saitoh, & B. J. van Wees, Nature Mater. 11, 391-399 (2012).
2. H. Yu, et al. Phys. Rev. B 95, 104432 (2017).
3. D. Prananto, Y. Kainuma, K. Hayashi, N. Mizuochi, K. Uchida, & T. An, Probing thermal magnon current via nitrogen-vacancy centers in diamond. Preprint at https://arxiv.org/abs/2007.13433 (2020).