Perpendicular Magnetic Anisotropy of Co2FexMn1−xSi Heusler Alloy Ultra-Thin Films

Abstract

Film thickness, composition, and buffer layer dependences of perpendicular magnetic anisotropy (PMA) were investigated for ultrathin Co <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> Mn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</sub> Si Heusler alloy films. The perpendicular magnetization was achieved when the thickness of the Co <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> MnSi on the Pd buffer layer was 0.6 and 0.8 nm. For Co <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> FeSi, only a 0.6 nm thick film exhibited perpendicular magnetization. Effective uniaxial magnetic anisotropy energy (Keffu ) was 1-2 × 106 erg/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . From the buffer layer dependence, it was revealed that perpendicular magnetization of Co <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> FeSi films was not achieved for a MgO or Cr buffer layer. These results imply that contributions from the Pd/Heusler alloy interface plays an important role in the PMA of ultrathin Co <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> Mn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</sub> Si Heusler alloy films.