Inhomogeneous electronic states associated with charge-orbital order/disorder in BaV_(10)O_(15) probed by photoemission spectromicroscopy

摘要

We have performed scanning photoemission spectromicroscopy of BaV_(10)O_(15) across the metal-insulator transition at 123 K, which is accompanied by V 3d charge/orbital order and V trimerization. Nucleation of metallic domains is observed at the cleaved surface of BaV_(10)O_(15) single crystals, similar to Cr-doped V_2O_3 in which electronic configurations of Cr~(3+) and V~(3+) are the same as those of V~(2+) and V~(3+) in BaV_(10)O_(15). Typical domain size is ～5–10 μm at 150 K, just above the transition temperature. The metallic domains continuously grow up to 240 K, well above the transition temperature. The temperature evolution of the metallic phase in BaV_(10)O_(15) is different from that of Cr-doped V_2O_3, probably due to the charge degrees of freedom in BaV_(10)O_(15).