Spin disordered resistivity of the heusler Ni2MnGa-based alloys

Electrical resistivity of the selected Heusler off-stoichiometric (NiCo)2Mn(GaIn) alloys was studied in a wide range of temperature and magnetic field. A step-like change of resistivity (?? ?24 ??cm) was detected in the offstoichiometric Ni1:85Mn1:21Ga0:94 alloy at temperature of martensitic structural transition. This ?? is much more significant than one in the stoichiometric Ni2MnGa alloy. In the case of the off-stoichiometric (NiCo)2Mn(GaIn) alloys, an enormous change of resistivity, ???200 ??cm, accompanies the structural transition. Simultaneously, the maximum of the spin disordered resistivity ?sd(T) of austenite phase of the alloys is slightly dependent on composition of the alloy and vary from ? 30 ??cm up to ? 45 ??cm, in good agreement with theoretical calculations. Due to high sensitivity of the structural transition temperature of the alloys to magnetic field, the very pronounced magnetoresistance effects have been observed in the studied alloys.