The samples ofLa8/9Sr1/45Na4/45MnO3 （LSNMO）/x/2（Sb2O3） were prepared by the solid-state reaction method. The electric transport properties and the temperature stabil-ity of magnetoresistance （MR） of the samples ...The samples ofLa8/9Sr1/45Na4/45MnO3 （LSNMO）/x/2（Sb2O3） were prepared by the solid-state reaction method. The electric transport properties and the temperature stabil-ity 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-temper-ature （MR-T） curves. The results indicate that the p-Tcurves 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 sam-ples in the low temperature range, MR increases continu-ously 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 perov-skite manganite and insulator, which can enhance the tem-perature 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 tem-perature 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.展开更多
The transport properties and magnetoresistance of electron-doped manganate / insulator composites （Lao.sTeo.2MnO3）l-x/（ZrO2）x （x = 0, 0.3, and 0.5） are investigated. It is found that the metal-insulator transiti...The transport properties and magnetoresistance of electron-doped manganate / insulator composites （Lao.sTeo.2MnO3）l-x/（ZrO2）x （x = 0, 0.3, and 0.5） are investigated. It is found that the metal-insulator transition temperature of this system shifts to a lower value as the ZrO2 content increases. The introduction of ZrO2 enhances both the domain scattering and electron relative scattering in the metal transport region. In the adiabatic small polaron hopping transport region, the thermal activation energy seems invariable regardless of the ZrO2 content. The applica- tion of a magnetic field promotes the charge transportation capabilities of the composites, and the magnetoresistance is enhanced with an increase of the ZrO2 content. This could be attributed to the more remarkable modification effect of magnetic field on ordering degree in the composites than in pure Lao.sTe0.2MnO3.展开更多
基金financially supported by the National Natural Science Foundation of China(No.19934003)the Natural Science Foundation of the Education Bureau of Anhui Province,China(Nos.KJ2011A259 and KJ2012Z404)+1 种基金Anhui Key Laboratory of Spintronics and Nano-materials Program(Nos.2010YKF01 and 2010YKF04)the Professors’and Doctors’ Research Startup Foundation of Suzhou University(Nos.2011jb01 and 2010jb02)
文摘The samples ofLa8/9Sr1/45Na4/45MnO3 （LSNMO）/x/2（Sb2O3） were prepared by the solid-state reaction method. The electric transport properties and the temperature stabil-ity 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-temper-ature （MR-T） curves. The results indicate that the p-Tcurves 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 sam-ples in the low temperature range, MR increases continu-ously 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 perov-skite manganite and insulator, which can enhance the tem-perature 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 tem-perature 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.
基金Project supported by the National Natural Science Foundation of China (Grant No.61078057)the Northwestern Polytechnical University Foundation for Fundamental Research,China (Grant Nos.JC201048 and JC201155)
文摘The transport properties and magnetoresistance of electron-doped manganate / insulator composites （Lao.sTeo.2MnO3）l-x/（ZrO2）x （x = 0, 0.3, and 0.5） are investigated. It is found that the metal-insulator transition temperature of this system shifts to a lower value as the ZrO2 content increases. The introduction of ZrO2 enhances both the domain scattering and electron relative scattering in the metal transport region. In the adiabatic small polaron hopping transport region, the thermal activation energy seems invariable regardless of the ZrO2 content. The applica- tion of a magnetic field promotes the charge transportation capabilities of the composites, and the magnetoresistance is enhanced with an increase of the ZrO2 content. This could be attributed to the more remarkable modification effect of magnetic field on ordering degree in the composites than in pure Lao.sTe0.2MnO3.
