Structural phase transition in the heavy fermion system Cu_6Ce

本文利用液氮和液氦储存库的透射电子显微镜，详细研究了重费米子系统CeCu6相变的结晶学特征。电子显微镜样品的制备采用离子稀释法。当温度降低时，在170K附近出现一维调制结构，而不是目前报道的从正交到单斜晶系的转变。调制结构的特征是调制方向几乎平行于[410]方向，在104K时其周期约为15 nm。此外，从弹性常数C_(66)的晶格软化和离子减薄方法制备样品过程中引入的晶格缺陷两个方面讨论了调制结构出现的物理来源。

In the present work, crystallographic features of phase transition in The heavy fermion system CeCu_6 have been in detail investigated by means of transmission electron microscopy equipped with both liquid nitrogen and liquid helium reservoirs. Specimens for electron microscopy were prepared by an ion-thinning method. When the temperature is lowered, a one-dimensional modulated structure appears around 170 K instead of the orthorhombic-to-monoclinic transition reported so far. Features of the modulated structure are that a direction of the modulation is nearly parallel to the [410] direction and its period is about 15 nm at 104 K. Further, a physical origin of the appearance of the modulated structure is discussed in relation to both a lattice softening of the elastic constant C_<66> and lattice defects introduced during the preparation of the specimen by the ion-thinning method.