Investigation of the metal-insulator transition in a thin manganite film by STM/STS

The colossal magnetoresistance (CMR) effect in manganite thin films is accompanied by a metal to insulator transition (MIT) in these samples. In this work a thin film of (La1-0.375Pr0.375)0.7Ca0.3MnO3 was grown by the metal-organic aerosol deposition technique on MgO substrates and investigated by transport measurements and scanning tunnelling microscopy (STM) and spectroscopy (STS) as a function of temperature. With these techniques we were able to compare the local electronic properties of the film with the global transport behavior. We observed an electronic phase separation at low temperatures and in the vicinity of the MIT. The metallic conductivity at low temperatures can be attributed to a double exchange mechanism while the insulating regions can be interpreted by a charge ordered high temperature phase.