Analysis of the interface in Al/Al-oxide/M/Al(M=Fe, Ni) junctions by inelastic-tunneling spectroscopy

摘要

Inelastic-electron-tunneling spectroscopy (IETS)was used to investigate the electron states of the interfaces ofAl/Al-oxide/Fe(D_(Fe))/Al and Al/Al-oxide/Ni(D_(Ni))/Al tunneljunctions. The conductance curves for all junctions showed aminimum around the zero-bias voltage. The IET spectra showed astrong positive peak around 4 mV, corresponding to the minimumof conductance curves, while another broad peaks was observedfor junctions with D_(Ni), D_(Fe)≧10?. The peak position wasdifferent from that assigned to the Al-O LO phonon modeobserved for Al/Al-oxide/Al junctions. It was confirmed bymagnetization measurements that a ferromagnetic layer wasformed for films with D_(Ni)≧30? and D_(Fe)≧10?. Theseresults were investigated in relation to the direct and inelastictunneling process due to magnons.