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

In this paper, 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 C) and density of states over large surface areas with size up to mm 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. Finally, 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] ;  [1] ;  [2] ;  [3]
  1. Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division
  2. Illinois Inst. of Technology, Chicago, IL (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Division. High Energy Physics Division
Publication Date:
Grant/Contract Number:
AC02-06CH11357; FWP 50335
Type:
Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 86; Journal Issue: 9; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Orgs:
Illinois Inst. of Technology, Chicago, IL (United States)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; Niobium; Josephson junctions; Surface conductivity; Superconductive tunneling; Superconducting metals
OSTI Identifier:
1356979