MBE法により作製したMnPt/NiFe二層膜の交換異方性  [in Japanese] Exchange Anisotropy in MBE-Grown MnPt/NiFe Bilayers  [in Japanese]

Exchange anisotropy in MnPt(30nm)/NiFe(5nm) bilayers was investigated for films growth by the MBE method on SrTiO_3(100) substrates at temperatures of T_g=25℃, 100℃, 200℃, 300℃. In-situ reflection high-energy electron diffraction observations and ex-situ X-ray diffraction measruements revealed that the MnPt layers grown on NiFe(100) have (100) orientations for T_g=25℃ and 100℃, while they have random orientations for T_g=200℃ and 300℃. Superlattice lines due to the formation of a CuAu-I type ordered structure were observed during the growth of the MnPt layer for all growth temperatures. The (100)-oriented MnPt/NiFe bilayer films were found to have an exchange anisotropy field (H_ex) of 220 Oe (corresponding to an exchange anisotropy energy of J=〜0.9erg/cm^2) and a coercivity (H_C) of 〜43 Oe. On the other hand, the films with random orientation showed almost zero H_<ex> and a rather large H_C of 〜600 Oe.