Magnon excitation of CoFe/Al-oxide/CoFe ferromagnetic tunnel junctions

Abstract Inelastic-electron-tunneling (IET) spectroscopy has been applied to investigate the magnon-induced inelastic tunneling process for Ta/Ni 80 Fe 20 /Cu/Ni 80 Fe 20 /IrMn/Co 75 Fe 25 /Al-oxide/Co 75 Fe 25 /Ni 80 Fe 20 /Ta ferromagnetic tunnel junctions. For the junction with the oxidation time, t ox =40 s , which is the exact time to oxidize the 8 A Al, the subtraction spectrum of the IET spectra between the parallel and anti-parallel magnetization configurations clearly showed two peaks at ±3 and ±16 mV showed. On the other hand, the spectrum for the junction with t ox =120 s showed a broad peak at around 18 mV and a plateau at zero-bias. This was caused by the change of the correlation length of magnon inelastic excitation due to the over oxidation of the bottom electrode.