New first-order phase transition in high-purity ytterbium metal

A first-order magnetic phase transition has been observed in high-purity Yb metal. It is characterized by a paramagnetic-to-diamagnetic transition with a large degree of hysteresis between 100 and 360 degrees K, and appears to be associated with an fcc-hcp martensitic transformation. The occurrence of this transition is characteristic of high-purity metal and has not been previously reported. Several other properties such as the specific heat at 0 and 106 kOe, the volume and resistance changes the low-temperature resistivity, x-ray data, and the pressure and strain dependence of the transition are discussed. The diamagnetic phase is not superconducting above 0.015 degrees K. The fee phase was obtained from the hcp phase by applying strain a room temperature and was also investigated. It shows a strongly temperature-dependent paramagnetic susceptibility down to 1.4 degrees K, but no magnetic ordering could be detected down to 1.0 degrees K.