Thermally driven magnon valves TmIG/Au/TmIG with perpendicular magnetic anisotropy*

The use of magnons to carry, transport, and process information could lead to faster processing of information free of Joule heating and, with a phase extra degree of freedom since magnons are quanta of spin waves. Like the conventional spin valves, magnon valves are trilayers used to control the flow of magnon currents with the potential to become the building block of magnonics devices. In this work, we fabricated magnon valves TmIG/Au/TmIG with perpendicular magnetic anisotropy (PMA). The PMA is an advantageous feature that allows a higher density of data storage in recording media and facilitates the control of the magnetic state of a thin film via spin-transfer torque and magnon-transfer torque. For exciting magnon currents through the valve, a longitudinal thermal gradient was applied to the trilayer as a spin Seebeck voltage was detected through the inverse spin Hall effect in a platinum electrode film deposited on the top of the structure. The PMA magnon valves showed three distinct levels for controlling the flow of magnons. These results shed light on the use of spin waves in computing devices.