High Pressure Synthesis & Superconductivity of Ytterbium Polyhydrides

Ytterbium polyhydrides were synthesized through in-situ high pressure laser heating techniques utilizing a diamond anvil cell. The temperature dependence of resistance measurement at high pressure demonstrates that the sample undergoes a superconducting transition at 11.5 K at 180 GPa. The investigation of SC under magnetic field indicates that the upper critical field at zero temperature \mu_0H_\rm c2(0) is \sim 5 Tesla. From the analysis of the in-situ high pressure X-ray diffraction experiments, the observed superconductivity is proposed to arise from the Pm\bar3n Yb_4H_23 phase. It is speculated that the low superconducting transition temperature T_\rm c in Yb_4H_23 might be associated with the unusual local magnetic moment in Yb at pressure.