Berlin 2015 – scientific programme
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O: Fachverband Oberflächenphysik
O 79: Scanning Probe Techniques: STM
O 79.2: Talk
Thursday, March 19, 2015, 10:45–11:00, HE 101
Determining absolute values of the critical Josephson current from Josephson STM experiments — •Berthold Jäck1, Matthias Eltschka1, Markus Etzkorn1, Christian R. Ast1, and Klaus Kern1,2 — 1Max-Planck Institute for Solid State Research, D-70569 Stuttgart — 2École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne
In Josephson junctions the critical Josephson current i0 directly relates to the superconducting order parameter. Hence, Josephson Scanning Tunneling Microscopy (JSTM) has high potential as a local probe of superconductor physics, addressing questions such as the pairing symmetry of non-conventional superconductors [1]. However, extracting absolute values for i0 from experiments renders difficult since both the surrounding environment and temperature strongly change the junction characteristics. Here, we present results on the Josephson effect in vanadium tunnel junctions using an STM that operates at a temperature of 15 mK [2]. Employing P(E)-theory as given in Reference [3], which considers the coupling to the environment and temperature effects, we can fit our experimental data. From this fit we find values of i0 being in good agreement to values calculated from theory [4], which represents a fundamental step towards the realization of JSTM.
[1] J.Smakov et al., Phys. Rev. B 64, 212506 (2001)
[2] M.Assig et al., Rev. Sci. Instrum. 84, 033903 (2013)
[3] G.-L.Ingold and H.Grabert, Europhys. Lett. 14, 371 (1991)
[4] V.Ambegaokar and A.Baratoff, Phys. Rev. Lett. 10, 11 (1963)