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

为了了解CeNiSn化合物的本征基态，在一种高质量的单晶上测量了其在磁场中的热学和磁学性质。提纯晶体的比热明显依赖于a轴方向的电场，而脏样品的电场依赖性较小，电子比热除以低于2K的温度C_e_1/T在零场中基本不变。然而，随着温度的进一步降低，在0.5K以下，Ce_1/T略有增加，这表明在E_F附近的赝隙底部有一个峰结构。场中的Ce_1/T有很大的降低，表明在Ik以下，刚性带图不再真实。在这项研究中，我们得出结论，CeNiSn是一种新型的反常金属，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.