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Title: Dependence of Andreev reflection and Schottky barriers on GaMnAs/Nb interface treatment

We studied the interfacial contact between GaMnAs and superconducting Nb micro-structures both with and without removing the native GaMnAs surface oxide. Our results show that a strong Schottky barrier forms at the interface when the oxide layer is left between Nb and GaMnAs. This barrier can be confused for Andreev Reflection and erroneously used to extract spin polarization. A simple acid etch is shown to remove the oxide film, thus decreasing the interface resistance, removing the Schottky barrier, and causing a clear Andreev reflection effect. One key recommendation for point contact Andreev reflection studies is to push the tip hard enough into contact and verify that the total resistance is not too high.
Authors:
; ;  [1] ; ;  [2]
  1. Department of Physics, Miami University, Oxford, Ohio 45056 (United States)
  2. Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States)
Publication Date:
OSTI Identifier:
22410123
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ELECTRIC CONDUCTIVITY; FILMS; GALLIUM COMPOUNDS; INTERFACES; LAYERS; MANGANESE ARSENIDES; MICROSTRUCTURE; NIOBIUM; OXIDES; REFLECTION; SPIN ORIENTATION; SUPERCONDUCTORS