Dresden 2009 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 15: Correlated Electrons: Metal-Insulator Transition 2

TT 15.2: Talk

Tuesday, March 24, 2009, 09:45–10:00, HSZ 301

Scanning tunneling spectroscopy across the insulator-to-metal transition in La_0.67Ca_0.33MnO₃ thin films — •Silvia Seiro^1,2, Yanina Fasano^2,3, Ivan Maggio-Aprile², Edmond Koller², Rolf Lortz^2,4, and Øystein Fischer² — ¹MPI-CPfS, Nöthnitzer Str. 40, 01187 Dresden, Germany — ²DPMC-University of Geneva, Quai Ernest-Ansermet 24, 1211 Geneva, Switzerland — ³Centro Atómico Bariloche, Av. E. Bustillo 9500, 8400 S. C. de Bariloche, Argentina — ⁴Department of Physics, The Hong Kong University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong

We present the temperature evolution of scanning tunneling spectra of La_0.67Ca_0.33MnO₃ thin films across the insulator-to-metal transition. A depletion in normalized conductance is observed over an energy range of a few hundred meV around the Fermi level. This depletion globally narrows upon cooling but is still present in the metallic phase. The link to macroscopic transport behavior is provided by the tunnel conductance at zero bias, which decreases upon cooling in the insulating phase, reaches a minimum close to the insulator-to-metal transition temperature and increases on cooling in the metallic phase. These results are interpreted in terms of dynamical short-range antiferromagnetic/charge order correlations.