MAGNETORESISTANCE IN ERCO2 AND HOCO2 SINGLE-CRYSTALS

The longitudinal magnetoresistance along the principal crystallographic directions in single crystals of ErCo2 and HoCo2 compounds has been measured in the range of field-induced first-order phase transition at temperatures above the spontaneous magnetic ordering temperature, T(C). The sharp decrease of electrical resistivity (DELTArho/rho up to -50%) is observed at critical fields, H(C). In ErCo2, the critical fields have different values along the principal crystallographic directions and the H(C)(T) dependences are nonlinear. For HoCo2 the absence of critical fields anisotropy and linear H(C)(T) dependences are observed. The behaviour of the electrical resistivity in an applied magnetic field at T > T(C) for both compounds is generally associated with suppression of the spin fluctuations at metamagnetic phase transitions.