高スピン分極フルホイスラー合金薄膜とスピンエレクトロニクスデバイス

抄録

  The recent development of the study on half-metallic full-Heusler alloy thin films and their application to spin-electronics devices are reviewed. The progress of preparation technique of Co-based full-Heusler alloy films with high L2₁ structural order has made it possible to obtain higher spin-polarization than that of typical transition metals and alloys (Co, CoFe, etc.). Resulting tunnel magnetoresistance in magnetic tunnel junctions exceeds 60% at room temperature. Our recent results on the current-perpendicular-to-plane magnetoresistance (CPP-GMR) devices with Co₂MnSi films are also shown. The resistance change-area product (ΔRA) at room temperature was 19 mΩμm², which is one order of magnitude larger than those in previously reported trilayer systems, resulting in the MR ratio of 2.4%. The enhanced ΔRA is considered to originate from the large spin polarization in a high-quality L2₁ Co₂MnSi film.