Anomalous Hall conductivity and magnetoresistance in epitaxial La0.67Ca0.33MnO3−δ thin films

The longitudinal magnetoresistance ${\rho }_{\mathrm{xx}}$ and Hall resistivity in-plane ${\rho }_{\mathrm{xy}}$ were simultaneously measured on an epitaxial ${\mathrm{La}}_{\mathrm{0.67}}{\mathrm{Ca}}_{\mathrm{0.33}}{\mathrm{MnO}}_{\mathrm{3-\delta }}$ thin film as a function of temperature at several magnetic fields. The zero-field resistivity ${\rho }_{\mathrm{xx}}$ reaches a maximum at $T_p\text{=225\hspace{0.17em}}\mathrm{K}$ which is very close to the Curie temperature $T_c\text{=221\hspace{0.17em}}\mathrm{K}$ determined by linearly extrapolating the reciprocal of the magnetization ${\mathrm{[M}}^{\text{−1}}\mathrm{(T)]}$ data to zero. The amplitude of the ${\rho }_{\mathrm{xx}}$ peak is reduced while the position of $T_p$ moves to higher temperatures as the external magnetic field is increased. The measurements of the Hall effect show that the carrier is holelike, and the carrier density is about 0.004 per unit cell above $T_C,$ which corresponds to the contribution of 1% of holes of ${\mathrm{Mn}}^{\mathrm{4+}}$ ions. ${\rho }_{\mathrm{xy}}$ depends strongly on temperature and magnetic field. An extraordinary ${\rho }_{\mathrm{xy}}$ peak in the vicinity of ${\rho }_{\mathrm{xx}}$ peak $T_P$ and Hall sign reversal in the temperature range of 210–240 K have been observed. These anomalous behaviors of Hall effect are discussed in the frame of skew-scattering theory.