中文摘要：

采用传统固相反应法制备钙钛矿型锰氧化物（La0.8Eu0.2）4/3Sr5/3Mn2O7多晶样品,X-射线衍射分析表明,样品（La0.8Eu0.2）4/3Sr5/3Mn2O7结构呈现良好的单相.通过磁化强度随温度的变化曲线（M-T）、不同温度下磁化强度随磁场的变化曲线（M-H）和电子自旋共振谱发现：在300 K以下,随着温度的降低,样品先后经历了二维短程铁磁有序转变（T2DC≈282K）、三维长程铁磁有序转变（T3D C≈259K）、奈尔转变（T N≈208K）和电荷有序转变（T CO≈35K）;样品（La0.8Eu0.2）4/3Sr5/3Mn2O7在T N以下,主要处于反铁磁态;在T3DC达到370 K时,样品处于铁磁-顺磁共存态,在370 K以上时样品进入顺磁态.此外,分析电阻率随温度的变化曲线（ρ-T）得到：样品在金属-绝缘转变温度（TP≈80K）附近出现最大磁电阻值,其位置远离T3D C,表现出非本征磁电阻现象,其磁电阻值约为61%.在T CO以下,电阻率出现明显增长,这是由于温度下降使原本在高温部分巡游的e g电子开始自发局域化增强所致.通过对（La0.8Eu0.2）4/3Sr5/3Mn2O7的ρ-T曲线拟合,发现样品在高温部分的导电方式基本遵循小极化子的导电方式.

英文摘要：

Samples of（La0.8Eu0.2）4/3Sr5/3Mn2O7 were prepared by solid state reaction method. X-ray diffraction patterns indicated that the sample shows no any asymmetry and no any trace of secondary phase. The magnetization curve as a function of temperature（M-T）, the magnetization versus magnetic field（M-H） at different temperatures, and the electron spin resonance spectrum have been detected. The magnetization measurement reveals that with lowing temperature, all of the samples undergo a complex magnetic transition. They transform from the two-dimensional short-range ferromagnetic order at T2 D C≈ 282 K, and enter the three-dimensional long-range ferromagnetic state at T3 D C≈ 259 K. Then they step into the antiferromagnetic state at T N ≈ 208 K and enter electric charge temperature order at T CO≈ 35 K. The antimagnetic phase is found in the sample（La0.8Eu0.2）4/3Sr5/3Mn2O7 below T N. When T3 D C= 370 K, the paramagnetic phase and antimagnetic phase co-exist. When T3 D C is above 370 K, only paramagnetic phase exists in the sample. Besides, through electrical resistivity versus temperature curve ρ-T, the sample shows the maximum magnetization electrical resistivity when metal-insulator transition temperature is reached T P ≈ 80 K, T P being far from T3 D C. And the transition shows the phenomenon of intrinsic magnetization electrical resistance, MR ≈ 61%.The resistance begins to increase below T CO. Because of the lowing temperature, the itinerant electron e g becomes increasingly spontaneously localized. One can see from the fitted ρ-T curves that（La0.8Eu0.2）4/3Sr5/3Mn2O7 in high temperature range is in accordance with the small polaron mode range hopping conduction.