Magnon and phonon assisted tunneling in a high-magnetoresistance tunnel junction using Co$_{75}$Fe$_{25}$ ferromagnetic electrodes

摘要

Magnetoelectric properties of the spin-valve-type tunnel junction of Ta(5\nm)/Ni$_{79}$Fe$_{21}$ (25 nm)/Ir$_{22}$Mn$_{78}$ (10 nm)/Co$_{75}$Fe$_{25}$ (4nm)/Al (0.8 nm)-oxide/Co$_{75}$Fe$_{25}$ (4 nm)/Ni$_{79}$Fe$_{21}$ (20 nm)/Ta(5 nm) are investigated both experimentally and theoretically. It is shown thatboth magnon and phonon excitations contribute to the tunneling process.Moreover, we show that there are two branches of magnon with spin $S=1/2$ and3/2 respectively. The theoretical results are in good agreement with theexperimental data.