Effect of Magnetic Impurities on Superconductivity in LaH.

Polyhydrides are a novel class of superconducting materials with extremely high critical parameters, which is very promising for sensor applications. On the other hand, a complete experimental study of the best so far known superconductor, lanthanum superhydride LaH , encounters a serious complication because of the large upper critical magnetic field H (0), exceeding 120-160 T. It is found that partial replacement of La atoms by magnetic Nd atoms results in significant suppression of superconductivity in LaH : each at% of Nd causes a decrease in T by 10-11 K, helping to control the critical parameters of this compound.

Transformation of diamond to fullerene-type onions at pressure 70 GPa and temperature 2400 K.

We report the observation of a phase transition of diamond to denser than diamond carbon phase composed from 2 to 3 fullerene-type shells of onions. Raman spectra indicate the fullerene-type of the onions shells. The onions phase is a stable phase in a diamond instability zone of a phase diagram of carbon at pressure 70 GPa and temperature 2400 K.