Structural, electronic, and magnetic properties of undoped and aliovalent-ion(Ca, F)-doped LaOFeP, which undergo superconducting transitions at transitiontemperatures (Tc) 4-7 K [Kamihara et al, J. Am. Chem. Soc. 128, 10012, (2006)],were investigated. Tc of the samples varied from 2.4 to 5.5 K in the undopedsamples, and was increased up to ~7 K by Ca- and F-doping. The Tc increases arecorrelated with a decrease in the lattice volume. LaOFeP exhibits paramagnetismin the normal conducting state. Photoemission spectroscopy combined withfirst-principle band calculations clarified that Fe 3d (dz2 + (dxz, dyz))orbitals hybridized with P 3p to form a Fermi surface. The band calculationsalso suggest that the 3d electron of the Fe in LaOFeP is basically in thelow-spin configuration, and that the spin moment of LaOFeP is almost quenched,leading to the paramagnetism of the itinerant electrons.
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