Fingerprint of dynamical charge/spin correlations in the tunneling spectra of colossal magnetoresistive manganites

S. SEIRO; Y. FASANO; I. MAGGIO-APRILE; E. KOLLER; R. LORTZ; O. FISCHER

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

Rapid Communications

Año: 2009 vol. 80 p. 100404 - 100407

0163-1829

We present temperature-dependent scanning tunneling spectroscopy measurements onLa1−xCaxMnO3 (x ∼ 0.33) films with different degrees of biaxial strain. A depletion in normalizedconductance around the Fermi level is observed both above and below the insulator-to-metaltransition temperature TMI, for weakly as well as highly-strained films. This pseudogap-like depletionglobally narrows on cooling. The zero-bias conductance decreases on cooling in the insulatingphase, reaches a minimum close to TMI and increases on cooling in the metallic phase, followingthe trend of macroscopic conductivity. These results support a recently proposed scenario in whichdynamical short-range antiferromagnetic/charge order correlations play a preeminent role in thetransport properties of colossal magnetoresistive manganites [R. Yu et al., Phys. Rev. B 77,214434 (2008)].