Regensburg 2019 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 22: Quantum dots and wires: Transport properties

HL 22.7: Vortrag

Dienstag, 2. April 2019, 15:30–15:45, H34

Thickness dependence of the magnetic field induced metal-insulator transition in graphite — •Laetitia Paula Bettmann, Jose Luis Barzola Quiquia, Markus Stiller, and Pablo Esquinazi — Division of Superconductivity and Magnetism, Felix-Bloch Institute for Solid State Physics, University of Leipzig, 04103 Leipzig, Germany

We have measured the temperature dependence of the resistance and magnetoresistance of bulk and multigraphene samples prepared from a natural graphite sample from Sri Lanka. The samples were measured at different constant magnetic fields in order to observe the well-known magnetic-field-induced metal-insulator transition in graphite. Our results indicate that the transition has a thickness dependence, i.e. in the case of thin samples (thickness less than 30 nm) this effect vanishes. We attribute the field induced metal-insulator transition to the presence of metallic-like two-dimensional interfaces formed between the crystals, which disappear when the sample thickness is of the order of the single crystalline regions of the sample. Our experimental results can be well understood using a model, which takes explicitly into account the interfaces contributing in parallel to the semiconducting crystalline regions.