Electronic structures of the charge-ordering manganite ${\mathrm{Nd}}_{1-x}{\mathrm{Sr}}_x{\mathrm{MnO}}_3(x\sim 0.5)$ have been studied by resonant and high-resolution photoemission. The Mn $2p$ (Nd $3d)$ resonant photoemission confirmed the Mn $3d$ (Nd $4f)$ states hybridized with the O $2p$ states. The high-resolution Mn $3p$ resonance spectra show a clear transition from the metal to the charge-ordered insulator for $x=0.5\mathrm{}$ upon cooling while a Fermi cutoff is seen for $x=0.47\mathrm{}$ at all temperatures, suggesting that the transition is induced by a subtle competition between the charge-ordering instability and the double-exchange interaction. Temperature and filling dependence of the spectra implies that the electronic states change not gradually but suddenly at the phase boundary.

• Received 10 November 1998

DOI:https://doi.org/10.1103/PhysRevB.59.15528