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High resolution X-ray powder diffraction studies have shown SrRhO3 to transform from an orthorhombic Pnma structure at room temperature through an intermediate Imma phase to a tetragonal I4/mcm structure near 800 °C. The orthorhombic Imma phase exists over a very limited temperature range, of less than 20°. The diffraction data suggests the Pnma to Imma transition is continuous and demonstrates that the Imma–I4/mcm transition is first order. [Copyright &y& Elsevier]

Abstract: Co nuclear quadrupole resonance (NQR) measurements were performed on the bilayer hydrate cobaltate compound under hydrostatic pressures to study the pressure effect on the superconducting (SC) and magnetic properties. We found that the hydrostatic pressure increases the NQR frequency and suppresses the SC transition temperature . The relationship between and observed in the present pressure-dependent measurements is different from that observed in sample-dependent NQR measurements. Nuclear spin–lattice relaxation rate was also measured under several pressures. The results indicate that the magnetic fluctuations are suppressed with applying pressures. The pressure effect on can be understood as the suppression of magnetic fluctuations, which act as the glue to form the cooper pairs. From the pressure effect on asymmetric parameter of the electric-field gradient, we suggest a possible explanation for the difference between sample dependence and pressure dependence. [Copyright &y& Elsevier]

Abstract: The nuclear quadrupole resonance (NQR) frequency of Co nuclei and the nuclear spin–lattice relaxation rate were measured on several bilayered hydrate (BLH) () with variety of superconducting (SC) and magnetic transition temperatures, and , together with non-SC mono-layered hydrate (MLH) (). In the high temperature region above 70K, in all the samples follows the same temperature dependence which is interpreted as the pseudogap behavior. In the BLH compounds, increases with decreasing temperature below 70K, and the values of at are large in high- samples. The magnetic ordering is ascertained from the observation of the prominent divergence of at in the samples whose NQR frequency is higher than 12.5MHz. The temperature dependence of is found to be consistently expressed by a unique function with two fitting parameters. We analyze the temperature dependence of on the basis of this function, and investigate the relationship between the magnetic fluctuations and superconductivity in the BLH compounds. [Copyright &y& Elsevier]

Abstract: We have studied the electronic structure near the Fermi level of the layered cobaltate superconductor Na0.35CoO2·1.3H2O using laser-excited ultrahigh-resolution photoemission spectroscopy (PES). In the normal state, we observed the formation of a pseudogap with an energy scale of ∼20meV. Across the superconducting transition, we observed the leading-edge shift at 3.5K compared to that at 10K, indicating superconducting gap (SC gap) opening having a gap value Δ of 0.5–0.7meV. The energy scale of the SC gap is ∼20 times smaller than that of the pseudogap, suggesting the existence of competing order parameters at low temperatures. [Copyright &y& Elsevier]

We have carried out 99/101Ru and 63/65Cu nuclear magnetic resonance experiments in order to investigate magnetic and electronic properties of the magnetic superconductor RuSr2RECu2O8 (RE=Gd, Eu and Y). The two kinds of 99/101Ru signals were observed in the magnetically ordered state for each system, suggesting a charge segregation of Ru5+ (S=3/2) and Ru4+ (S=1) ions in the RuO2 layers. The internal field at the Cu sites is revealed to be of the order of kilo Oe, indicating weak magnetic interactions between the CuO2 and RuO2 planes. The temperature dependence of nuclear spin-lattice relaxation time T1 of 63Cu in RE=Y shows a ‘spin gap’ like behavior, suggesting the system is under-doped. [Copyright &y& Elsevier]