Photoemission study of (V)O (=Cr,Ti)

Mo, S.-K.*; Kim, H.-D.*; Denlinger, J. D.*; Allen, J. W.*; Park, J.-H.*; Sekiyama, Akira*; Yamasaki, Atsushi*; Suga, Shigemasa*; Saito, Yuji  ; Muro, Takayuki*; Metcalf, P.*

We present high-resolution bulk-sensitive photoemission spectra of (V)O (=Cr,Ti). The measurements were made for the paramagnetic metal (PM), paramagnetic insulator (PI), and antiferromagnetic insulator (AFI) phases of (V)O. In the PM phase, we observe a prominent quasiparticle peak in general agreement with theory, which combines dynamical mean-field theory with the local density approximation. For both the PI and AFI phases, the vanadium 3 parts of the valence spectra are not simple one peak structures. For the PI phase, there is not yet a good theoretical understanding of these structures. Spectra taken in the same phases with different compositions show interesting monotonic changes as the dopant concentration increases, regardless of the dopant species. With increased Cr-doping, the AFI phase gap decreases and the PI phase gap increases.