Synthesis of ferromagnetic tgr; phase of Mn‐Al films by sputtering

摘要

Mn‐Al films have been prepared by dc magnetron sputtering and their crystallographic characteristics, magnetic properties, electrical resistivity, and internal stress have been investigated. The films deposited when substrate temperatureTswas below 100 °C and above 170 °C exhibit a high‐temperature egr; phase and bgr;‐Mn–like structure, respectively. Films of a ferromagnetic tgr; phase were synthesized with Mn content in the range of 58–62 at.  andTsof about 150 °C. Existence of CuAu‐type superstructure in the tgr; phase was confirmed by a change of electrical resistivity rgr; of deposited films. The films deposited at aTsof about 150 °C exhibit minimum value of 180 mgr;OHgr; cm. Lattice constantaandcof the tetragonal tgr;‐phase crystallites in the films were in the range of 3.582–3.592 A˚ and 3.941–3.968 A˚, respectively, while those of the bulk alloy were 3.580 and 3.940 A˚, respectively. The maximum value of saturation magnetization of the films was 120 emu/cc, being as small as about one fourth of that of bulk alloy. This may be caused by elongation of lattice constants and coexistence of nonmagnetic egr; phase.