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采用传统固相反应法制备双层锰氧化物Nd1.15Tb0.05Sr1.8Mn2O7多晶样品,通过测量样品的X射线衍射谱、磁化强度随温度变化曲线(M-T曲线)以及电阻率随温度变化曲线(ρ-T曲线),对其磁性和电输运性质进行了研究。结果表明,样品随温度的升高先后经历了四个磁转变点:奈尔温度点(TN≈50 K)、电荷有序温度点(TCO≈67 K)、居里温度点(TC≈107 K)和类Griffiths温度点(TG≈275 K)。在低温部分样品处于反铁磁-铁磁共存态,表现出了团簇自旋玻璃行为;在TC到TG温度范围内,样品处于铁磁-顺磁共存态,即存在类Griffiths相;在TG温度以上,样品处于纯顺磁态。其电输运性质表明,随温度的升高,样品的磁电阻率降低,没有发生金属-绝缘转变。通过对115 K~300 K温度范围内的ρ-T曲线拟合发现,样品在高温部分基本遵循三维变程跳跃的导电方式。
The solid state reaction method was used to prepare Nd1.15Tb0.05Sr1.8Mn2O7 double-layered manganese oxide polycrystalline samples. The X-ray diffraction spectra of the samples, the magnetization curves with temperature (MT curve) and the curves of resistivity with temperature ρ-T curve), its magnetic and electrical transport properties were studied. The results show that the sample undergoes four magnetic transition points with increasing temperature: the Nel temperature point (TN≈50 K), the charge order temperature point (TCO≈67 K), the Curie temperature point (TC≈107 K ) And Griffiths temperature point (TG ≈ 275 K). In the low temperature part of the sample in the antiferromagnet - ferromagnetic coexistence state, showing the cluster spin glass behavior; in the TC to TG temperature range, the sample is in the ferromagnetic - paramagnetic coexistence state that exists Griffiths phase; TG Above the temperature, the sample is in pure paramagnetic state. The electrical transport properties show that with the increase of temperature, the magnetic resistivity of the sample decreases and no metal-insulator transition occurs. By fitting the ρ-T curve in the temperature range from 115 K to 300 K, it is found that the sample basically follows the conduction mode of three-dimensional jump in high temperature.