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 degreesC 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.