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Title: Point contact tunneling spectroscopy apparatus for large scale mapping of surface superconducting properties

We describe the design and testing of a point contact tunneling spectroscopy device that can measure material surface superconducting properties (i.e., the superconducting gap Δ and the critical temperature T{sub C}) and density of states over large surface areas with size up to mm{sup 2}. The tip lateral (X,Y) motion, mounted on a (X,Y,Z) piezo-stage, was calibrated on a patterned substrate consisting of Nb lines sputtered on a gold film using both normal (Al) and superconducting (PbSn) tips at 1.5 K. The tip vertical (Z) motion control enables some adjustment of the tip-sample junction resistance that can be measured over 7 orders of magnitudes from a quasi-ohmic regime (few hundred Ω) to the tunnel regime (from tens of kΩ up to few GΩ). The low noise electronic and LabVIEW program interface are also presented. The point contact regime and the large-scale motion capabilities are of particular interest for mapping and testing the superconducting properties of macroscopic scale superconductor-based devices.
Authors:
;  [1] ;  [2] ;  [1] ;  [3]
  1. Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439 (United States)
  2. Illinois Institute of Technology, Chicago, Illinois 60616 (United States)
  3. (United States)
Publication Date:
OSTI Identifier:
22482797
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 86; Journal Issue: 9; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; DENSITY OF STATES; ELECTRIC CONTACTS; GOLD; MAPPING; SPECTROSCOPY; SUPERCONDUCTING JUNCTIONS; SURFACES; TRANSITION TEMPERATURE; TUNNEL EFFECT