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Title: Field dependence of the vortex core size probed by scanning tunneling microscopy

We study the spatial distribution of the density of states (DOS) at zero bias N(r) in the mixed state of single and multigap superconductors. We provide an analytic expression for N(r) based on deGennes' relationship between DOS and the order parameter that reproduces well scanning tunneling microscopy (STM) data in several superconducting materials. In the single gap superconductor β-Bi2 Pd, we find that N(r) is governed by a length scale ξH = $$\sqrt{Φ0/2πH}$$ which decreases in rising fields. The vortex core size $C$ ∝ (d Δ/dr|r→0)₋1 differs from ξH by a material dependent numerical factor. The new data on the tunneling conductance and vortex lattice of the 2H-NbSe1.8S0.2 show the in-plane isotropic vortices, suggesting that substitutional scattering removes the in-plane anisotropy found in the two-gap superconductor 2H-NbSe2. We fit the tunneling conductance of 2H-NbSe1.8S0.2 to a two gap model and calculate the vortex core size $C$ for each band. We find that $C$ is field independent and has the same value for both bands. We also analyze the two-band superconductor 2H-NbSe2 and find the same result. Lastly, we conclude that, independently of the magnetic field induced variation of the order parameter values in both bands, the spatial variation of the order parameter close to the vortex core is the same for all bands.
Authors:
 [1] ;  [2] ;  [2] ;  [2] ;  [3] ;  [3] ;  [3] ;  [4]
  1. Autonomous Univ. of Madrid (Spain). Inst. of Materials Science Nicolas Cabrera Condensed Matter Physics and Center (IFIMAC), Low Temperature Lab.; Autonomous Univ. of Madrid (Spain). Associated Unit of Low Temperature and High fields Magneticos
  2. Autonomous Univ. of Madrid (Spain). Inst. of Materials Science Nicolas Cabrera Condensed Matter Physics and Center (IFIMAC), Low Temperature Lab.; Autonomous Univ. of Madrid (Spain). Associated Unit of Low Temperature and High fields Magneticos
  3. Univ. of Valenci, Paterna (Spain). Inst. of Molecular Science (ICMol)
  4. Ames Lab., Ames, IA (United States)
Publication Date:
Report Number(s):
IS-J-9079
Journal ID: ISSN 2469-9950; PRBMDO
Grant/Contract Number:
AC02-07CH11358; FIS2014-54498-R; MAT2014-56143-R; 679080; MAT2014-52919-REDC; MDM2015-0538; MDM-2014-0377
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 94; Journal Issue: 1; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Spanish Ministry of Economy and Competitiveness; European Union EU; COLCIENCIAS Programa Doctorados en el Exterior Convocatoria; European Research Council (ERC)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1326846
Alternate Identifier(s):
OSTI ID: 1275980