Magnetoresistance and AC susceptibility studies in a re-entrant spin glass AuFe

Abstract

The longitudinal magnetoresistances (Delta/rho/rho) has been measured in AuFe (18 at.%) alloy in the temperature range 4.2-200K and in magnetic fields (H) of up to 10 kG. The data have been analysed in the framework of the theory based on the vector mean-field model leading to the coexistence of spin glass and ferromagnetic orders at low temperatures. In the coexistence regime and at low fields, it is found that Delta rho/rho varies as H⁶7/, thereby indirectly implying a quadratic dependence of Delta rho/rho on magnetisation according to the above theory. The measurements of real and imaginary parts of AC susceptibility are also reported.