Control of magnon-photon coupling by spin torques

Magnons, the quantum mechanical excitation of spin waves, in a magnetically order system can couple with microwave photons via dipolar interaction demonstrating level repulsion (coherent coupling) of the hybridized modes. There can be also a coalescence of hybridized modes resulting in level attraction (dissipative coupling). However, efficient control of magnon-photon coupling and toggling between coherent and dissipative coupling is not well understood [1]. Here, we demonstrate the control of magnon-photon coupling by spin torques [2]. We examine the role of spin torques in the magnon photon coupling by classically integrating the generalized Landau-Lifshitz-Gilbert equation with RLC equation in which a phase correlation between dynamic magnetization and microwave current through combined Ampere and Faraday effects are considered. Our model suggests that an on-demand manipulation of the magnon-photon coupling strength can be achieved for current densities of the order as small as 10⁵ A/cm² and materials with moderate Gilbert damping of the order 10⁻³. Moreover, we discuss the special case, where it is possible to achieve dissipative coupling by spin torque.



Research supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-SC0020308.



References:

[1] Igor Proskurin and Robert L. Stamps Phys. Rev. B 103, 195409 (2021)

[2] Anish Rai and Benjamin Jungfleisch J. Magn. Magn. Mater. 571, 170558 (2023)