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Title: Influence of multiband sign-changing superconductivity on vortex cores and vortex pinning in stoichiometric high- T c   CaKFe 4 As 4

We use a scanning tunneling microscope to study the superconducting density of states and vortex lattice of single crystals of CaKFe 4As 4. This material has a critical temperature of T c = 35 K, one of the highest among stoichiometric iron based superconductors (FeBSCs), and is comparable to T c found near optimal doping in other FeBSCs. We observe quasiparticle scattering from defects with a pattern related to interband scattering between zone centered hole sheets. We measure the tunneling conductance in vortex cores and find a peak due to Caroli–de Gennes–Matricon bound states. The peak is located above the Fermi level, showing that CaKFe 4As 4 is a clean superconductor with vortex core bound states close to the so-called extreme quantum limit. We identify locations where the superconducting order parameter is strongly suppressed due to pair breaking. Vortices are pinned at these locations, and the length scale of the suppression of the order parameter is of order of the vortex core size. Finally, as a consequence, the vortex lattice is disordered up to 8 T.
Authors:
 [1] ;  [2] ;  [2] ;  [3] ;  [2] ;  [2] ;  [1] ;  [1]
  1. Autonomous Univ. of Madrid (Spain). Lab. de Bajas Temperaturas y Altos Campos Magnéticos, Dept. de Física de la Materia Condensada, Inst. de Ciencia de Materiales Nicolas Cabrera and Condensed Matter Physics Center (IFIMAC), Unidad Asociada UAM/CSIC
  2. Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Physics & Astronomy
  3. Ames Lab., Ames, IA (United States)
Publication Date:
Report Number(s):
IS-J-9594
Journal ID: ISSN 2469-9950; PRBMDO
Grant/Contract Number:
679080; AC02-07CH11358; GBMF4411
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 97; Journal Issue: 13; 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). Materials Sciences & Engineering Division; Gordon and Betty Moore Foundation; USDOE
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1433657
Alternate Identifier(s):
OSTI ID: 1430776

Fente, Anton, Meier, William R., Kong, Tai, Kogan, Vladimir G., Bud'ko, Sergey L., Canfield, Paul C., Guillamon, Isabel, and Suderow, Hermann. Influence of multiband sign-changing superconductivity on vortex cores and vortex pinning in stoichiometric high- Tc CaKFe4As4. United States: N. p., Web. doi:10.1103/PhysRevB.97.134501.
Fente, Anton, Meier, William R., Kong, Tai, Kogan, Vladimir G., Bud'ko, Sergey L., Canfield, Paul C., Guillamon, Isabel, & Suderow, Hermann. Influence of multiband sign-changing superconductivity on vortex cores and vortex pinning in stoichiometric high- Tc CaKFe4As4. United States. doi:10.1103/PhysRevB.97.134501.
Fente, Anton, Meier, William R., Kong, Tai, Kogan, Vladimir G., Bud'ko, Sergey L., Canfield, Paul C., Guillamon, Isabel, and Suderow, Hermann. 2018. "Influence of multiband sign-changing superconductivity on vortex cores and vortex pinning in stoichiometric high- Tc CaKFe4As4". United States. doi:10.1103/PhysRevB.97.134501.
@article{osti_1433657,
title = {Influence of multiband sign-changing superconductivity on vortex cores and vortex pinning in stoichiometric high- Tc CaKFe4As4},
author = {Fente, Anton and Meier, William R. and Kong, Tai and Kogan, Vladimir G. and Bud'ko, Sergey L. and Canfield, Paul C. and Guillamon, Isabel and Suderow, Hermann},
abstractNote = {We use a scanning tunneling microscope to study the superconducting density of states and vortex lattice of single crystals of CaKFe4As4. This material has a critical temperature of Tc = 35 K, one of the highest among stoichiometric iron based superconductors (FeBSCs), and is comparable to Tc found near optimal doping in other FeBSCs. We observe quasiparticle scattering from defects with a pattern related to interband scattering between zone centered hole sheets. We measure the tunneling conductance in vortex cores and find a peak due to Caroli–de Gennes–Matricon bound states. The peak is located above the Fermi level, showing that CaKFe4As4 is a clean superconductor with vortex core bound states close to the so-called extreme quantum limit. We identify locations where the superconducting order parameter is strongly suppressed due to pair breaking. Vortices are pinned at these locations, and the length scale of the suppression of the order parameter is of order of the vortex core size. Finally, as a consequence, the vortex lattice is disordered up to 8 T.},
doi = {10.1103/PhysRevB.97.134501},
journal = {Physical Review B},
number = 13,
volume = 97,
place = {United States},
year = {2018},
month = {4}
}