We have studied the chemical potential shift and changes in the electronic density of states near the Fermi level $\left(E_F\right)$ as a function of carrier concentration in ${\mathrm{Pr}}_{1-x}{\mathrm{Ca}}_x\mathrm{Mn}{\mathrm{O}}_3$ (PCMO, $0.2⩽x⩽0.65$) through the measurements of photoemission spectra. The results showed that the chemical potential shift was suppressed for $x\gtrsim 0.3$, where the charge-exchange (CE) type antiferromagnetic charge-ordered state appears at low temperatures. We consider this observation to be related to charge self-organization such as stripe formation on a microscopic scale in this composition range. Together with the previous observation of monotonous chemical potential shift in ${\mathrm{La}}_{1-x}{\mathrm{Sr}}_x\mathrm{Mn}{\mathrm{O}}_3$, we conclude that the tendency toward the charge self-organization increases with decreasing bandwidth. In the valence band, spectral weight of the Mn $3d$ $e_g$ electrons in PCMO was transferred from $\sim 1\mathrm{eV}$ below $E_F$ to the region near $E_F$ with hole doping, leading to a finite intensity at $E_F$ even in the paramagnetic insulating phase for $x\gtrsim 0.3$, probably related with the tendency toward charge self-organization. The finite intensity at $E_F$ in spite of the insulating transport behavior is consistent with fluctuations involving ferromagnetic metallic states.

• Received 13 June 2006

DOI:https://doi.org/10.1103/PhysRevB.74.064419