Regensburg 2019 – scientific programme

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MA: Fachverband Magnetismus

MA 5: Surface magnetism and magnetic coupling phenomena (joint session MA/O/TT)

MA 5.7: Talk

Monday, April 1, 2019, 11:00–11:15, H53

Scanning Seebeck Tunneling Microscopy — Cody Friesen, Hermann Osterhage, Johannes Friedlein, Anika Schlenhoff, Roland Wiesendanger, and •Stefan Krause — Department of Physics, University of Hamburg, Germany

The field of spin caloritronics is specifically concerned with effects that arise in the presence of a temperature gradient, and their effect on spin-dependent electronic transport. The advent of increasingly detailed techniques for nano-scale fabrication, measurement, and manipulation have led to an improved understanding of spin caloritronic effects, and their potential uses in engineering sensors and devices at all size scales, e.g. waste-heat recycling and efficient computing.

Within this field, the thermally induced Seebeck tunneling of electrons is a fundamental effect. In our experiments, it is studied in a metal-vacuum-metal junction using scanning tunneling microscopy (STM). Selective heating of the tip with a laser generates a well-defined temperature difference at the tunnel junction. The thermovoltage between the tip and the sample is measured with atomic-scale lateral resolution and related to the band structure of the junction, as revealed by local tunneling spectroscopy. Tunnel current rectification experiments in compensated conditions allow for a direct measurement of the Seebeck coefficient without the need for tip heating, thereby realizing Seebeck mapping on the atomic scale. The STM studies will be presented and discussed in terms of thermally induced tunneling across a single-atom ideal vacuum barrier.
C. Friesen et al., J. Phys. D: Appl. Phys. 51, 324001 (2018).