We report the pressure-induced superconductivity in the noncentrosymmetric heavy-fermion CeRhSi3. The superconductivity emerges above about 12 kbar even though the antiferromagnetic ordering persists. Furthermore, another anomaly is observed in the superconducting phase. The anomalous magnetic field-temperature phase diagram with a high upper critical field suggests that an unconventional superconductivity is realized in CeRhSi3.

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X-ray emission (XES) and absorption (XAS) spectra near the B-K edge were measured on single-crystalline AlB2 compound which is an isostructural diboride of superconducting MgB2. The partial density of states (PDOS) of B-2pσ and pπ orbitals were derived from the polarization dependence of XES and XAS spectra. There are considerable amounts of PDOS near the Fermi energy in AlB2 similarly to that in MgB2, but there are almost no PDOS in pσ orbitals of AlB2 near the Fermi energy, i.e., a pseudo-gap in pσ state and a broad metallic state in pπ state are observed. The present result indirectly supports scenarios that the pσ holes play an important role in the occurrence of superconductivity in MgB2. The overall features of PDOS were found to be in good agreement with the result of band calculation of AlB2, but a small discrepancy in the Fermi energy is observed, which is attributed to the Al vacancy in the compounds, i.e., the estimated concentration is Al0.93B2. KEYWORDS: MgB 2 , AlB 2 , single crystal, partial density of state, pσ and pπ orbitals, X-ray emission and absorption spectroscopy