Tunnel magnetoresistance oscillations in a ferromagnet-insulator-ferromagnet system

A model of spin-dependent transport of electrons through a ferromagnet-insulator-ferromagnet structure is developed. It takes into account the image forces, tunnel barrier parameters, and effective masses of an electron tunneling in the barrier and in the ferromagnetic electrode in the free electron approximation. Calculations for an iron-aluminum oxide-iron structure show that, with an increase in the bias voltage, the tunnel magnetoresistance decreases monotonically and then breaks into damped oscillations caused by the interference of the electrons’ wave functions in the conduction region of the potential barrier. The image forces increase the tunnel magnetoresistance by two or three times.