Orbitally Ordered State in Y1-xCaxTiO3 (0<x≤0.5)

Orbitally ordered states of a Ti t 2 g -electron in Y 1- x Ca x TiO 3 (0 < x ≤0.5) have been systematically investigated by the resonant X-ray scattering (RXS) technique near the Ti K -edge. The RXS intensities at 1 s →3 d transition energy (pre-edge) reflecting the 3 d -orbital ordering markedly decrease with increasing Ca concentration toward the ferromagnetic–paramagnetic phase boundary ( x FP ∼0.15). The intensity remaining above x FP decreases gradually and almost disappears at the metal–insulator transition ( x MI ∼0.4). Namely, it is suggested that the orbital ordering is strongly suppressed toward x FP , and vanishes at  x MI . The Ca concentration dependence of the Jahn–Teller distortion determined by X-ray structural analysis is consistent with the orbital state obtained by the RXS experiment.