SmFeAsO的简便合成及其物理性能表征
Synthesis of SmFeAsO by an Easy and Versatile Route and its Physical Property Characterization
摘要：
报道了SmFeAsO的合成、结构、电输运和热容。标题化合物是通过化学计量的FeAs、Sm和Sm_2 O_3在真空（10 ~（-5）Torr）石英管中于1100 ℃下延长（72小时）退火一步包封而合成的。所合成的化合物以四元晶系结构结晶，具有P4/nmm空间群，晶格参数a = 3.93726（33）A和c = 8.49802（07）A。电阻（R-T）测量表明，在140 K以下，化合物呈现出类似基态自旋密度波（SDW）的金属阶跃。标题化合物的热容CP（T）测量显示在140 K左右的异常，这让人想起化合物的SDW排序。在较低温度下，CP（T）在4.5K附近显示出明显的峰。在低于20 K的较低温度下，Cp（T）也在7特斯拉的外加场下测量。结果表明，在4.5K处出现的CP（T）峰是由于Sm ~（3+）自旋的反铁磁（AFM）有序化所致。这些结果与Sm在Sm_（2-x）Ce_xCuO_4中的有序性相一致。
英文摘要：
We report synthesis, structure, electrical transport and heat capacity of SmFeAsO. The title compound is synthesized by one-step encapsulation of stoichiometric FeAs, Sm, and Sm2O3 in an evacuated (10-5 Torr) quartz tube by prolong (72 hours) annealing at 1100oC. The as synthesized compound is crystallized in tetragonal structure with P4/nmm space group having lattice parameters a = 3.93726(33) A and c = 8.49802(07) A. The resistance (R-T) measurements on the compound exhibited ground state spin-density-wave (SDW)-like metallic steps below 140 K. Heat capacity CP(T) measurements on the title compound, showed an anomaly at around 140 K, which is reminiscent of the SDW ordering of the compound. At lower temperatures the CP(T) shows a clear peak at around 4.5 K. At lower temperature below 20 K, Cp(T) is also measured under an applied field of 7 Tesla. It is concluded that the CP(T) peak at 4.5 K is due to the anti-ferromagnetic(AFM) ordering of Sm3+ spins. These results are in confirmation with ordering of Sm in Sm2-xCexCuO4.
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