Magnetoresistance of the La0.7Ca0.3MnO3 single crystal

Abstract

The dependence of the resistance ρ of the La0.7Ca0.3MnO3 single crystal on the temperature (in a range of 77 0 and is determined by changes in the resistance with changing magnetization orientation with respect to the crystallographic axes; in high magnetic fields, the magnetoresistance is negative Δρ/ρ < 0, since it is the suppression of spin fluctuations in the magnetic field that plays the principal role. The phase transition from the ferromagnetic to paramagnetic state is a first-order transition close to the second-order one. In the transition range, the magnetoresistance is determined by the resistivity in the zero field ρ(T) and by the shift of the transition temperature T C(H) in the magnetic field. In the paramagnetic state, the resistivity ρ(T) has an activation character; similarly to the magnetoresistance of other lanthanum manganites, the magnetoresistance of this single crystal is controlled by a change in the activation energy in the magnetic field.