We present temperature-dependent scanning tunneling spectroscopy measurements on ${\text{La}}_{1-x}{\text{Ca}}_x{\text{MnO}}_3$ $\left(x\sim 0.33\right)$ films with different degrees of biaxial strain. A depletion in normalized conductance around the Fermi level is observed both above and below the insulator-to-metal transition temperature $T_{\text{MI}}$, for weakly as well as highly strained films. This pseudogaplike depletion globally narrows on cooling. The zero-bias conductance decreases on cooling in the insulating phase, reaches a minimum close to $T_{\text{MI}}$ and increases on cooling in the metallic phase, following the trend of macroscopic conductivity. These results support a recently proposed scenario in which dynamical short-range antiferromagnetic/charge order correlations play a preeminent role in the transport properties of colossal magnetoresistive manganites [R. Yu et al., Phys. Rev. B 77, 214434 (2008)].

• Received 31 October 2008

DOI:https://doi.org/10.1103/PhysRevB.80.100404