Fe/AlOx-NOLを用いたNCMR素子におけるマイクロ波発振の特徴

概要

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We investigated Spin Torque Oscillation (STO) excited by spin-polarized currents in Current-Perpendicular-to-Plane (CPP) spin-valve devices with Fe/AlOx-Nano-Oxide Layer (NOL) that had Nano-Contact MagnetoResistance (NCMR). From the R-H curve, at the applied current, the magnetization state of the free layer is affected by an Oersted field and Spin Transfer Torque (STT). At positive current, the dependence of applied field demonstrated a blue shift, while, at negative current it demonstrated a red shift. Under 250-350 Oe multiple modes, low-level oscillations and wide FWHM were observed, while, under 360-500 Oe single modes, high-level oscillations and narrow FWHM were observed at positive current. Moreover, under 250-350 Oe, the dependence of applied current on oscillation frequency demonstrated a red or blue shift, while, under 360-500 Oe, it demonstrated blue shift. The blue shift oscillations under the applied current were considered to have originated from coherent out-of-plane precession near nano-contacts on the free layer side.
社団法人　日本磁気学会の論文