MAGNETORESISTANCE OF THE RANDOM ANISOTROPIC CO70.4FE4.6SI15B10 ALLOY

Longitudinal magnetoresistance measurements in Co70.4Fe4.6Si15B10 are reported for applied magnetic fields H varying from 0 to +/- 15 Oe. Two regimes were observed: one which increases with H2 and another which decreases with M2 for higher fields. The maximum in the magnetoresistance is observed for H = 2.4 Oe for samples annealed for 15 min at 573 K in a transverse magnetic field of 2 kOe. The measured variation in R (H) from H = 0 to 2.4 was about 0.2%. The value of H = 2.4 is nearly the same field where a field-induced transition in the magnetization was observed. For samples annealed in the absence of the magnetic field the H2 term is the only one observed, The present results can be accounted for by the rotational model for uniaxial transverse anisotropy and the results are also in agreement with the random anisotropy model used to discuss the irreversibility and the field-induced transition.