A Ferromagnetic Oxide Semiconductor as Spin Injection Electrode in Magnetic Tunnel Junction

A magnetic tunnel junctions composed of room temperature ferromagnetic semiconductor rutile Ti 1- x Co x O 2-δ and ferromagnetic metal Fe 0.1 Co 0.9 separated by AlO x barrier showed positive tunneling magnetoresistance (TMR) with a ratio of ∼11% at 15 K, indicating that Ti 1- x Co x O 2-δ can be used as a spin injection electrode. The TMR decreased with increasing temperature and vanished above 180 K. TMR action at high temperature is likely prohibited by the inelastic tunneling conduction due to the low quality of the amorphous barrier layer and/or the junction interface.