Electric transport properties and temperature stability of magnetoresistance of composite system between La_8/9Sr_1/45Na_4/45MnO₃ and Sb₂O₃

Abstract

The samples of La_8/9Sr_1/45Na_4/45MnO₃ (LSNMO)/$\frac{x}{2}$(Sb₂O₃) were prepared by the solid-state reaction method. The electric transport properties and the temperature stability of magnetoresistance (MR) of the samples were studied through the measurements of X-ray diffraction patterns, resistivity–temperature (ρ–T) curves, mass magnetization–temperature (σ– T) curves, and magnetoresistance–temperature (MR–T) curves. The results indicate that the ρ–T curves of the original material LSNMO show two peaks, and the phenomenon of two peaks of ρ–T curves disappears for the composite samples, which can be explained by a competition between surface-phase resistivity induced by boundary-dependent scattering and body-phase resistivity induced by paramagnetism–ferromagnetism transition. For all the samples in the low temperature range, MR increases continuously with the decrease of temperature, which shows a characteristic of low-field magnetoresistance. However, MR basically keeps the same in the high temperature range. The paramagnetism–ferromagnetism transition is observed in the high temperature range due to a composite between perovskite manganite and insulator, which can enhance the temperature of MR appearance in the high temperature range and make it to appear near room temperature. For the sample with x = 0.12, MR remains constant at the value of 7.5 % in the temperature range of 300–260 K, which achieves a temperature stability of MR near room temperature. In addition, for the sample with x = 0.16, MR is above 6.8 % in the high temperature range of 318–252 K (∆T = 66 K). MR almost remains constant in this temperature range, which favors the practical application of MR.