Orbital states of V trimers in BaV10O15 detected by resonant x-ray scattering

BaV10O15 shows a structural phase transition associated with the trimerization of V ions at T-s = 123 K. We investigated the orbital states of V trimers using the technique of resonant x-ray scattering (RXS) near the V K-edge absorption energy. The ratio of the intensity between the pre-edge structure (1s to 3d transition) and the main-edge structure (1s to 4p transition) strongly depends on the reciprocal Q position of the scattering. We found that the Q position dependence is consistent with the model of orbital ordering proposed by Pen et al., [Phys. Rev. Lett. 78, 1323 (1997)].