Magnetism and Superconductivity of CePt_3Si and Ce_<1+x>Pt_<3+y>Si_<1+z>(Condensed Matter : Electronic Structure, Electrical, Magnetic and Optical Properties)

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We measured the dc magnetization, electrical resistivity, and ac magnetic susceptibility of a series of polycrystalline CePt_3Si samples whose compositions vary slightly from the stoichiometric composition. The sample that showed the most distinct antiferromagnetic transition at 2.2K was found to be Ce_<1.01>Pt_3Si annealed. This sample showed a clear bulk antiferromagnetic order at 2.2K even in both electrical resistivity and dc magnetization measurements, although the characteristic change in dc magnetization at 2.2K was found to be small and to be easily masked in other magnetic anomalies if they exist. Moreover, it had the largest residual resistivity ratio. We concluded that Ce_<1.01>Pt_3Si annealed has the intrinsic bulk properties of ideal CePt_3Si. In addition, we revealed that some anomalies arise as a result of the variation in composition. One is a ferromagnetic anomaly at 3.0K in the Pt-rich samples, and the other is an antiferromagnetic anomaly at 4.0K in the Pt-poor samples. The two magnetic anomalies seemed to appear in small domains in the samples that exhibited an antiferromagnetic order at 2.2K. To reveal the relationship between these magnetisms and superconductivity, we measured ac magnetic susceptibility down to 〜14mK. We found that the superconducting transition temperature is suppressed by the ferromagnetic anomaly.
社団法人日本物理学会の論文
2006-01-15