Regensburg 2025 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 24: Poster Scanning Probe Techniques: Method Development

O 24.6: Poster

Montag, 17. März 2025, 18:00–20:00, P2

Optimizing ESR-STM for mK Temperatures in a Closed-Cycle Dilution Refrigerator — •Luise Renz, Máté Stark, Jonas Arnold, Johannes Schwenk, Christoph Sürgers, Wolfgang Wernsdorfer, and Philip Willke — Physikalisches Institut (PHI), Karlsruhe Institute of Technology, Karlsruhe, Germany

Using Electron Spin Resonance (ESR) combined with Scanning Tunneling Microscopy (STM), electronic and magnetic properties of single atoms and molecules can be studied. However, the possibility of applying RF voltages to the tip often limits the achievable minimum temperature of the STM. We here describe an ESR-STM setup mounted in ultra-high vacuum (UHV) in a closed-cycle Dilution Refrigerator (DR). The focus here is on the wiring of the STM, the material choice and the filtering of the RF and DC cables with the goal of having a good transmission of the RF lines but nevertheless also mK-temperatures in the STM junction. The resulting bandwidth and transmission of these cables, the noise level of the STM as well as the electronic temperature of the STM junction, is presented. The electronic temperature is estimated on a Pb(111) crystal by evaluating the superconducting gap and the Josephson peak (using a superconducting tip).

Keywords: ESR-STM; Dilution Refrigator; Electronic Temperature