Author/Authors :
Matsumoto، نويسنده , , Rie and Hamada، نويسنده , , Yusuke and Mizuguchi، نويسنده , , Masaki and Shiraishi، نويسنده , , Masashi and Maehara، نويسنده , , Hiroki and Tsunekawa، نويسنده , , Koji and Djayaprawira، نويسنده , , David D. and Watanabe، نويسنده , , Naoki and Kurosaki، نويسنده , , Yoshinari and Nagahama، نويسنده , , Taro and Fukushima، نويسنده , , Akio and Kubota، نويسنده , , Hitoshi and Yuasa، نويسنده , , Shinji and Suzuki، نويسنده , , Yoshishige، نويسنده ,
Abstract :
We measured differential tunneling conductance (dI/dV, d2I/dV2) spectra of spin-valve-type magnetic tunnel junctions (MTJs) with a MgO(001) tunnel barrier layer and amorphous CoFeB ferromagnetic electrodes that show 315% magnetoresistance (MR) ratio at 4.3 K. The dI/dV spectra showed clear reduction in the conductance at around ±400 mV for a parallel magnetic configuration. Such anomalous spectra have never been observed for MTJs with an amorphous Al–O barrier. The d2I/dV2 spectra showed several distinct peaks between 5 and 100 mV. Magnon excitations are assigned to an origin of those peaks and thought to be a dominant process to reduce MR at finite bias voltage.
Keywords :
D. Tunneling , D. Electronic transport , D. Electronic band structure , A. Magnetic films and multilayers
