Co_2MnAl_<1-x>Si_xホイスラー合金の磁気抵抗効果  [in Japanese] Magnetoresistance of Co_2MnAl_<1-x>Si_x Heusler Alloys  [in Japanese]

The composition dependence of the magnetoresistance, resistivity, magnetization, and crystal structure were investigated for Co_2MnAl_<1-x>Si_x and A_2MnAl (A=Fe-Co, Co-Ni) Heusler alloys prepared by the rapid quenching method. The crystal structure of the alloys was B2 structure except for Co_2MnSi, which was L2_1 structure. Both GMR and AMR were observed in several alloys. The GMR exhibited a maximum at x=0.2 and A=Fe_<0.1>Co_<0.9>. The sign of the AMR was negative in several alloys. The composition dependence of the magnetoresistance, resistivity, and magnetization was calculated by using a simple model taking account of the reported DOS. The composition dependence of GMR and AMR is discussed.