La_(0.875)Na_(0.125)MnO_3外延膜的制备及CMR效应  

Preparation and CMR effect of Epitaxial Film La_(0.875)Na_(0.125)MnO_3

作　　者：韩立安[1] 王瑞平[1] 渊小春[1] 班丽瑛[1] 常琳[1] 孟泉水[1] 贺拥军[1] 

机构地区：[1]西安科技大学,陕西西安710054

出　　处：《稀有金属材料与工程》2008年第12期2169-2172,共4页Rare Metal Materials and Engineering

基　　金：国家自然科学基金(50572088);西安科技大学培育基金(200737)

摘　　要：通过射频磁控溅射法在单晶LaAlO3(100)衬底上成功地外延生长了膜厚为90.8nm的La0.875Na0.125MnO3薄膜。用X射线衍射仪、原子力显微镜、超导量子干涉仪、直流四探针法对其进行了表征。结果表明,薄膜为赝立方钙钛矿结构,具有良好的(100)外延取向和光滑表面。居里温度TC=275K。在居里温度附近,发生铁磁-顺磁转变。此材料呈现出一种典型的自旋玻璃特性,是由于应力造成的。薄膜的电阻率随温度变化的ρ-T曲线出现双峰。高温电阻峰TP1出现在居里温度附近,来源于铁磁金属体向顺磁绝缘体的转变。而低温电阻峰TP2出现在T=178K,是由于相分离引起的。在4T强磁场下,相分离现象消失。另外,薄膜的磁电阻曲线也呈现出双峰特征。Using magnetron sputtering method, La0.875Na0.125MnO3 film of 90.8 nm in thickness was epitaxially grown on LaAlO3 single-crystal substrate. The film was characterized by X ray diffraction, atom force microscope, superconducting quantum interference device and DC four probe. The results show that the thin film is a pseudo-cubic perofskite type structure with the well epitaxial direction of （100） and smooth surface. The Curie temperature Tc is 275 K. Near the Curie temperature, the magnetic properties exhibit a transition from ferromagnetic to paramagnetic. Additionally, the film exhibit a characteristic spin glass state, which is due to stress effects. Two peaks were observed in temperature dependence of resistivities. Tp1 is defined as high temperature resistivity peak and Tp2 is defined as low temperature resistivity peak. Tp1 correspond well with Tc owing to transition from ferromagnetic metal state to paramagnetic insulator state. In the meanwhile, the Tp2 peak at T=178 K may be interpreted as phase separation. The phenomenon of phase separation was disappeared when the magnetic field is 4 T. At the same time, the magnetoresistance curve was also appeared two peaks.

关 键 词：La0.875Na0.125MnO3外延膜 相分离 CMR效应 

分 类 号：O482.5[理学—固体物理] O484.1[理学—物理]