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Spatially resolved low‐temperature spectroscopy on niobium bulk samples
Author(s) -
Berthe R.,
Hartmann U.,
Heiden C.
Publication year - 1988
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/j.1365-2818.1988.tb01456.x
Subject(s) - niobium , superconductivity , condensed matter physics , materials science , spectroscopy , vortex , physics , quantum mechanics , metallurgy , thermodynamics
SUMMARY Using a low‐temperature STM, simultaneous measurements of the surface topography and of spatial variations in the current‐voltage characteristics have been performed on poly‐crystalline niobium bulk samples. A special electronic set‐up was developed which allows the tip bias to be swept at a constant tip position. From the resulting I ( V ) curves the actual magnitude of the superconducting energy gap is derived. The comparison of the surface morphology and gap distribution permits the detection of possible correlations between local variations in the superconductivity and in the topography. Upon the application of an external magnetic field, local variations of the gap are observed which have no topographic counterparts. This latter observation might indicate the existence of isolated vortices.