Realization of Multifunctional Bosonic Magnon Transistor via Thermal Phonon Gating

Magnons have demonstrated enormous potential for next-generation information technology, namely the ability to build quasiparticle low-power integrated circuits without the moving of electrons. An experimental bosonic magnon transistor with multifunction, low-loss, and full-wavelength control of propagating spin waves (magnon current) is developed in this work. Using a monolayer of graphene as the high-efficiency thermal phonon source and a low-loss electrically insulating ferrimagnetic single-crystalline yttrium iron garnet film as the propagating spin-wave channel, the presented transistor has three functioning regions of spin-wave modulation at full wavelength: prominent amplification, complete cut-off, and linear phase shift. The magnon-phonon-mediated nonequilibrium state created by the temperature gradient in this transistor works in two ways: when the thermal phonon flow is small, the positive thermal spin-torque induced by the longitudinal spin-Seebeck effect amplifies spin waves; when the thermal phonon flow is large, the magnon-magnon interaction due to nonequilibrium thermal magnon injection greatly contributes to spin-wave cut-off. Furthermore, linear adjustment of the spin-wave phase by creating a thermal phonon bath is demonstrated. These findings reveal that the numerous magnon-phonon coupling mechanisms in magnetic insulators offer a promising platform for the implementation of reconfigurable magnonic transistors.

Automated summary

This study develops a new type of magnonic transistor with multifunction, low loss, and full-wavelength control of propagating spin waves. It utilizes graphene and ferrimagnetic single-crystalline materials to achieve amplification and cut-off of spin waves through thermal phonon mediated nonequilibrium states. The findings also demonstrate the linear adjustment of spin-wave phase by creating a thermal phonon bath.