A phenomenological description of temperature dependence of magnetoresistance in La2/3Ca1/3MnO3-δ thin films

Abstract

The electrical resistance in zero magnetic field and magnetoresistance in different external magnetic fields have been measured in a temperature range of 77—300 K. It is found that the temperature dependence of magnetoresistance can be well described by a phenomenofogical formula of $$\rho (T) = \frac{1}{{\sigma (T)}} = \frac{1}{{(M/M_s )^2 + \beta ( - E_0 /k_B T)}}$$ where the fitting parameters α, β vary as the external magnetic fieldH changes,E 0 is the activation energy,E 0/k B = 1160 K,M s is the saturation magnetization, the temperature and magnetic field dependence ofM/M s is obtained by the mean-field expression.