Control of magnon-photon coupling by spin torques

Magnons, the quantum mechanical excitation of spin waves, in magnetically order system can couple with microwave photons via dipolar interaction demonstrating level repulsion (coherent coupling) of the hybridized modes. However, there can be also the coalescence of hybridized modes resulting in level attraction (dissipative coupling). This work examines the role of damping and field-like 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 analysis suggests that it is possible to enhance the coupling strength for level repulsion if a certain magnitude and direction of the dc current density is reached for an intermediate value of damping parameter (10^-3). However, the toggling between coherent and dissipative coupling is not possible using the spin torques.