A systematic structure search in the Ce-H system under pressure reveals novel stable phases with intriguing electronic properties. Several cerium hydrides, CeH4, CeH9, and CeH10, were found to be dynamically stable. Electron-phonon calculations coupled to Bardeen-Cooper-Schrieffer arguments indicate that they might be high-Tc superconductors. In particular, the maximum Tc values for F4¯3m-CeH9 and Fm3¯m-CeH10 are 142 K and 168 K at 94 GPa. These findings may pave the way for achieving room temperature superconductors in dense hydrogen-rich compounds.

The temperature dependence of the resistivity ρ(T ) of 122-Fe-pnictides is studied. The normal state resistivity ρ n (T ) is analyzed with the scaling method. It is found that the ρ n (T ) data can be scaled onto the universal curves for optimal, overdoped and underdoped samples, by using the energy scale , the resistivity ρ and the residual resistivity ρ 0 as the scaling parameters, where the universal curves can be described by an exponential function. The overall resistivity can be described by a uniform formula by taking the three-dimensional (3D) Aslamazov-Larkin (AL) fluctuation contribution into account, which is consistent with the two-channel scenario proposed for the cuprate superconductors.

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A direct method to calculate the activation energy from the resistance transition is proposed for high temperature superconductors (HTSCs). It is applied to Er-doped melted textured growth (MTG) YBa2Cu3O7−δ (YBCO) crystals. The activation energy is found to be U(T, H) = (Tp−T)m(H/H0)−β, with m = 2.1 ± 0.2 and β = 0.97. All the low temperature data are scaled onto a straight line by the plot of lnR/Rn versus , which supports the proposed method.