ANISOTROPIC ELECTRICAL-RESISTANCE IN NI76MN24 AND NI74MN24PT2 AMORPHOUS-ALLOYS

Magnetoresistance measurements have been carried out on the amorphous Ni-76 Mn-24 and Ni-74 Mn-24 Pt-2 thin film alloys at T = 4.2, 77 and 3 00 K for three different cases: (i) The applied magnetic field H paral lel to the current J (longitudinal magnetoresistance); (ii) the applie d field perpendicular to the current, but parallel to the film surface (Transverse magnetoresistance); (iii) the applied field perpendicular to the film surface (Normal magnetoresistance). The resistivity for H perpendicular to J in a saturating magnetic field (the field H = 20 k Oe is large enough to eliminate the magnetoresistance effect) has been observed to be dependent upon the direction of the field relative to the easy axis (z-axis) along which the magnetic anisotropy has been de veloped as being uniaxial in character. It was determined that the res istance anisotropy exhibits the same symmetry as the uniaxial magnetic anisotropy. The relationship between the magnetic anisotropy and the ferromagnetic anisotropy in resistivity is discussed. Furthermore, rep lacing some Ni atoms with Pt impurities has been observed to result in a decrease of ferromagnetic anisotropy in the resistivity. Some possi ble reasons for this are discussed as well.