Role of p-f hybridization in the metal-nonmetal transition of PrRu4P12

Electronic state evolution in the metal-nonmetal transition of PrRu4P12 has been studied by X-ray and polarized neutron diffraction experiments. It has been revealed that, in the low-temperature nonmetallic phase, two inequivalent crystal-field (CF) schemes of Pr3+ 4f(2) electrons with Gamma(1) and Gamma((2))(4)-ground states are located at Pr1 and Pr2 sites forming the bee unit cell surrounded by the smaller and larger cubic Ruion sublattices, respectively. This modulated electronic state can be explained by the p-f hybridization mechanism taking two intermediate states of 4f(1) and 4f(3). The p-f hybridization effect plays an important role in the electronic energy gain in the metal-nonmetal transition originated from the Fermi surface nesting.