High-Magnetoresistance Tunnel Junctions Using Co75Fe25 Ferromagnetic Electrodes

Tunnel magnetoresistance (TMR) effect and the applied voltage dependence of the TMR ratio in the tunnel junctions Ta(5 nm)/Ni79Fe21(3 nm)/Cu(20 nm)/Ni79Fe21(3 nm)/ Ir22Mn78(10 nm)/Co75Fe25(4 nm)/Al(0.8 nm)-oxide/Co75Fe25(4 nm)/ Ni79Fe21(20 nm)/Ta(5 nm) were investigated. MR ratio, effective barrier height and width, and breakdown voltage of the junctions can be remarkably enhanced after annealed at 300°C for an hour using Co75Fe25 as ferromagnetic electrodes and Cu as bottom conduction electrode. High MR ratio of 49.7% at room temperature and 69.1% at 4.2 K for the TMR junctions were observed.