Berlin 2008 – scientific programme

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MA: Fachverband Magnetismus

MA 28: Magnetic Thin Films III

MA 28.11: Talk

Thursday, February 28, 2008, 17:00–17:15, H 1012

Scanning Tunneling Microscopy and Spectroscopy Measurements on a (La_1−0.375Pr_0.375)_0.7Ca_0.3MnO₃ Thin Film — •Christin Kalkert, Lakshmana Sudheendra, Vasily Moshnyaga, Bernd Damaschke, and Konrad Samwer — I.Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen

One of the main goals of manganite physics is to reach an understanding of the metal-insulator transition and associated colossal magnetoresistance effect (CMR). Scanning tunneling microscopy (STM) and spectroscopy (STS) measurements may play an important role in explaining these phenomena since they resolve the spatial distribution and evolution of electronic states across the transition temperature.We have studied a (La_1−0.375Pr_0.375)_0.7Ca_0.3MnO₃ thin film epitaxially grown by metalorganic aerosol deposition on MgO substrate. STS measurements show a homogeneous insulating behavior at room temperature and high resolution STM measurements lead to the assumption that we are dealing with a charge ordered state. STM and STS measurements at temperatures below T_C yield an electronically phase-separated state with an insulating state showing the same conductivity as the homogeneous high temperature state coexisting with a metallic state. Close to T_C we have also observed phase separation. Here we see the high temperature state but also a phase with an intermediate conductivity. This work is supported by DGF via SFB 602 TPA2 and the Leibniz program.