采用传统固相法制备钙钛矿锰氧化物(La0.9Eu0.1)4/3Sr5/3Mn2O7多晶样品.通过XRD表明,样品(La0.9Eu0.1)4/3Sr5/3Mn2O7呈现单相性良好;通过对磁化强度随温度变化(M-T)、磁化强度在不同温度下随磁场变化曲线(M-H)和电子自旋共振ESR谱线表明,随着温度的升高,样品先后经历了三维长程铁磁有序转变点(TC3D≈75 K)和二维短程铁磁有序转变点(TC2D≈227 K),在TC3D与TC2D之间,系统处于铁磁与顺磁混合态;当温度达到360 K系统进入纯顺磁态,另外样品在低温区(TC3D以下)出现类团簇自旋玻璃特征.通过磁电阻随温度变化的ρ-T曲线,在T≈84 K附近,样品出现最大磁电阻.而且通过对(La0.9Eu0.1)4/3Sr5/3Mn2O7的ρ-T曲线拟合,得到样品在高温区域的导电方式为热激活模型.
Samples (La0.9 Eu0.1)4/3Sr5/3Mn2O7 were prepared by solid state reaction method.X-ray diffraction patterns indicated the sample shows no any asymmetry and no any trace of secondary phase.Through the magnetization curve with the temperature (M-T) and magnetization curve with magnetic field under different temperatures (M-H) and the ESR spectrum detection,it is found that,with temperature increasing,all the samples undergo a complex magnetic transition.They transform from the two-dimensional short-range ferromagnetic order at T2C2D ≈ 227 K and enter the three-dimensional long-range ferromagnetic state at TC3D ≈75 K.Between TC3Dand TC2D,both paramagnetic phase and antimagnetic phase exist.When T =360 K,paramagnetic phase appears in the sample.Besides,the sample reflects a characteristic of cluster spin glass at low temperature range which is under TC3D.Through electrical resistivity curve with the temperature p-T,the sample shows the max magnetization electrical resistivity when metal-insulator transition temperature T ≈ 84 K.It can be seen from the fitted p-T curves of (La0.9Eu0.1) 4/3Sr5/3Mn2O7 that the electron conducting mechanism in high temperature range is in accordance with thermal activated model.
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