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Title: Characterization of two different orientations of epitaxial niobium thin films grown on MgO(001) surfaces

Epitaxial Nb thin films deposited onto the same crystalline insulating surface can evolve in very different fashions depending on specific deposition conditions, thereby affecting their microstructure, surface morphology and superconducting properties. Here, we examine and compare the microstructure and ensuing surface morphology from two distinct Nb/MgO series each with its own epitaxial registry—namely Nb(001)/MgO(001) and Nb(110)/MgO(001)—leading to distinct surface anisotropy and we closely examine the dynamical scaling of the surface features during growth. We compare our findings with those in other metal/MgO epitaxial systems and for the first time, general scaling formalism is applied to analyze anisotropic surfaces exhibiting biaxial symmetry. Further, Power Spectral Density is applied to the specific problem of thin film growth and surface evolution to qualify the set of deposition conditions leading to smoother surfaces. We find good correlation between the surface morphology and microstructure of the various Nb films with superconducting properties such as their residual resistance ratio and lower critical field.
Authors:
;  [1] ; ;  [2] ;  [3]
  1. Department of Physics, The College of William and Mary, Williamsburg, Virginia 23187 (United States)
  2. Department of Applied Science, The College of William and Mary, Williamsburg, Virginia 23187 (United States)
  3. Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States)
Publication Date:
OSTI Identifier:
22217774
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 114; Journal Issue: 22; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANISOTROPY; CRITICAL FIELD; CRYSTAL STRUCTURE; DEPOSITION; EPITAXY; LAYERS; MAGNESIUM OXIDES; MICROSTRUCTURE; MORPHOLOGY; NIOBIUM; SPECTRAL DENSITY; SURFACES; THIN FILMS; TYPE-II SUPERCONDUCTORS