Tunneling Study of the Charge-Ordering Gap on the Surface of La${}_{0.350}$Pr${}_{0.275}$Ca${}_{0.375}$MnO${}_3$ Thin Films

Abstract

Variable temperature scanning tunneling microscopy/spectroscopy studies on (110) oriented epitaxial thin films of La${}_{0.350}$Pr${}_{0.275}$Ca${}_{0.375}$MnO${}_3$ are reported in the temperature range of 77 to 340 K. The films, grown on lattice matched NdGaO${}_3$ substrates, show a hysteretic metal-insulator transition in resistivity at 170 K. The topographic STM images show step-terrace morphology while the conductance images display a nearly homogeneous surface. The normalized conductance spectra at low temperatures (T$<$150 K) show an energy gap of 0.5 eV while for T$\ge$180 K a gap of 0.16 eV is found from the activated behavior of the zero bias conductance. The presence of energy gap and the absence of phase separation on the surface over more than 2 $\mu$m$\times$2 $\mu$m area contradicts the metallic behavior seen in resistivity measurements at low temperatures. We discuss the measured energy gap in terms of the stabilization of the insulating CO phase at the film surface.

arXiv comment5 pages, 5 figures To appear in Phys. Rev. B

References in corpus (13)

• Colossal Magnetoresistant Materials: The Key Role of Phase Separation
• Atomic-scale images of charge ordering in a mixed-valence manganite
• Thermal/Electronic Transport Properties and Two-Phase Mixtures in La_{5/8-x}Pr_{x}Ca_{3/8}MnO_{3}
• Intrinsic Inhomogeneities in Manganite Thin Films Investigated with Scanning Tunneling Spectroscopy
• Polarons and confinement of electronic motion to two dimensions in a layered transition metal oxide
• Effect of strain and electric field on the electronic soft matter in manganite thin films
• The effect of substrate induced strain on the charge-ordering transition in Nd_{0.5}Sr_{0.5}MnO_{3} thin films
• Full Bulk Spin Polarization and Intrinsic Tunnel Barriers at the Surface of Layered Manganites
• Multiphase segregation and metal-insulator transition in single crystal La(5/8-y)Pr(y)Ca(3/8)MnO3
• Optical Evidence of Multiphase Coexistence in Single Crystalline (La,Pr,Ca)MnO3
• A-site Ordering versus Electronic Inhomogeneity in CMR-Manganite Films
• Electronic phase separation in the rare earth manganates, (La1-xLnx)0.7Ca0.3MnO3 (Ln = Nd, Gd and Y)
• Scaled frequency-dependent transport in the mesoscopically phase-separated colossal magnetoresistive manganite La_{0.625-y}Pr_yCa_{0.375}MnO_3

Cited by in corpus (6)

• Study of Short-distance Spin and Charge Correlations and Local Density-of-States in the CMR regime of the One-Orbital Model for Manganites
• Structural and Magnetic Properties of Single Crystals of the Geometrically Frustrated Zirconium Pyrochlore, Pr2Zr2O7
• Images of metallic and insulating domains on the surface of a (La0.4Pr0.6)0.67Ca0.33MnO3 film
• Fingerprint of dynamical charge/spin correlations in the tunneling spectra of colossal magnetoresistive manganites
• Persistent metal-insulator transition at the surface of an oxygen-deficient, epitaxial manganite film
• Evidence of mobile carriers with Charge Ordering gap in Epitaxial Pr${}_{0.625}$Ca${}_{0.375}$MnO${}_3$ Thin Films