Strong phonon interaction between two distant magnetic films inserted into a cavity

Abstract

Phonon and magnon excitations can be modulated by magnetoelastic and magneto-optical coupling effects, respectively. The photons not only mediate the interaction between two distant magnetic films inserted into a cavity, but also affect the phonon excitations in each film by the magnetoelastic coupling. In this work, an indirect interaction mechanism is presented for the phonons in two distant magnetic films inserted into a cavity. Although the phonons in no way pass through a very long distance from one film to the other in a vacuum environment, they can establish a correlation between two films through the magneto-optical and magnetoelastic couplings in each film. This really corresponds to an indirect interaction. In this work, the relationship between the phonon interaction and the laser intensity is studied using a quantum theory. It is found that when the laser frequency is equal to magnon frequency and the laser intensity is in a certain range, this phonon interaction energy takes very large negative values so as to satisfy the application requirement. According to a generating functional integral approach, a formula for the phonon interaction energy is derived, and an experimental approach to detect this effect is suggested. This indirect interaction effect of phonons not only adds to our understanding of the essence of matter interaction, but also reveals some potential applications to the heat management of electronic devices, long-range transfer of heat energy, and ultrasonic signal transmission in a vacuum environment.