KONDO SEMI-METALLIC STATE OF CeNiSn IN HIGH MAG NETIC FIELDS AT LOW TEMPERATURES

为了了解该化合物的本征基态，在高质量的单晶上测量了CeNiSn的热学和磁性能。已经发现，纯化晶体的比热明显依赖于沿a轴的场，而脏样品的比热依赖较小。在零场下，电子比热除以温度C_e_1/T几乎保持恒定。随着温度的进一步降低，c__1 /T在0.5 K以下略有升高，表明在E_F周围的赝隙底部存在峰结构。在场中发现c__1 /T的大幅度减小，表明在I k以下刚性带图不再真实。场依赖性表明赝隙内的峰被外场坍缩。在这项研究中，我们得出结论，CeNiSn被归类为一种新型异常金属，而不是近藤绝缘体。

Thermal and magnetic properties of CeNiSn have been measured on a high-quality single crystals in magnetic fields in order to know the intrinsic ground state of this compound. The specific heat for the purified crystal has been found to remarkably depend on the field along the a axis in contrast with less field dependence for dirty samples.The electronic specific heat divided by temperature C_e_1/T below 2 K stays nearly constant in zero field. With further decreasing temperature, however, C_e_1/T slightly increases below 0.5 K, which suggests that there is a peak structure at the bottom of the pseudo-gap around E_F. The large reduction of C_e_1/T in the field has been found, suggesting that a rigid band picture is no longer realistic below I K.The field dependence indicates that the peak inside the pseudo-gap is collapsed by the external fields. In this study, we concluded that CeNiSn is classified a new-type anomalous metal instead of a Kondo insulator.