Berlin 2024 – scientific programme
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O: Fachverband Oberflächenphysik
O 11: Focus Session: Spins on Surfaces studied by Atomic Scale Spectroscopies II
O 11.4: Talk
Monday, March 18, 2024, 16:00–16:15, MA 004
YSR-STM thermometer for superconducting quasiparticle temperatures — •Ciprian Padurariu1, Sujoy Karan2, Haonan Huang2, Björn Kubala1,3, Christian R. Ast2, and Joachim Ankerhold1 — 1Institute for Complex Quantum Systems and IQST, Ulm University, Ulm, Germany — 2Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany — 3Institute of Quantum Technologies, German Aerospace Center (DLR), Ulm, Germany
The occupation of the quasiparticle continuum in a superconductor is of critical importance for the functionality of Josephson junction-based quantum devices. While significant progress has been made recently, the detection and removal (trapping) of quasiparticles remains a significant challenge. This talk will describe the design of a thermometer that detects the presence and effective temperature of superconducting quasiparticles. The device consists of a mK-STM functionalized with a single Yu-Shiba-Rusinov (YSR) state inside the gap. Transport between the tip and a clean superconducting substrate shows Zeeman-split peaks in the differential conductance associated to the YSR state [1]. The width of the peaks is sensitive to the effective temperature of quasiparticles above the gap. We show that this width manifests not only in the voltage-dependence, but also in the magnetic field- and exchange coupling-dependence of the current. This allows determining the effective temperature below the limit of the STM energy resolution.
[1] W.-V. van Gerven Oei, et al., "Magnetic impurities in spin-split superconductors", Phys. Rev. B 95, 085115 (2017).
Keywords: Yu Shiba Rusinov states YSR; atomic scale; superconducting quasiparticles; superconducting thermometer; magnetic impurity