SKM 2023 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 77: Scanning Probe Techniques: Method Development II
O 77.1: Vortrag
Donnerstag, 30. März 2023, 10:30–10:45, REC C 213
How cold is the junction of a millikelvin scanning tunnelling microscope? — Taner Esat1,2, Xiaosheng Yang1,2, Farhad Mustafayev1,2, Helmut Soltner3, Stefan Tautz1,2,4, and •Ruslan Temirov1,5 — 1Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Germany — 2Jülich Aachen Research Alliance (JARA), Jülich, Germany — 3Zentralinstitut für Engineering, Elektronik und Analytik (ZEA-1), Forschungszentrum Jülich, Germany — 4Experimentalphysik IV A, RWTH Aachen University, Aachen, Germany — 5University of Cologne, Institute of Physics II, Cologne, Germany
We employ a millikelvin scanning tunnelling microscope (STM) cooled to millikelvin temperatures by an adiabatic demagnetization refrigerator (ADR) to perform scanning tunnelling spectroscopy (STS) on an atomically clean surface of Al(100) in a superconducting state using normal-metal and superconducting STM tips. Varying the ADR temperatures between 30 mK and 1.2 K, we show that the temperature of the STM junction T is decoupled from the temperature of the surrounding environment Tenv. Simulating the Josephson current with the P(E) theory, we determine that Tenv ≈ 1.5 K, while fitting of the superconducting gap yields the lowest T ≈ 77 mK.