Magnetic memory structures using electric-field controlled interlayer exchange coupling (IEC) for magnetization switching

摘要

A magnetic memory structure employs electric-field controlled interlayer exchange coupling between a free magnetic layer and a fixed magnetic layer to switch a magnetization direction. The magnetic layers are separated by a spacer layer disposed between two oxide layers. The spacer layer exhibits a large IEC while the oxide layers provide tunnel barriers, forming a quantum-well between the magnetic layers with discrete energy states above the equilibrium Fermi level. When an electric field is applied across the structure, the tunnel barriers become transparent at discrete energy states via a resonant tunneling phenomenon. The wave functions of the two magnets then can interact and interfere to provide a sizable IEC. IEC can control the magnetization direction of the free magnetic layer relative to the magnetization direction of the fixed magnetic layer depending on the sign of the IEC, induced by a magnitude of the applied electric field above a threshold value.