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Title: Anisotropic type-I superconductivity and anomalous superfluid density in OsB 2

Here, we present a microscopic study of superconductivity in OsB 2, and discuss the origin and characteristic length scales of the superconducting state. From first-principles we show that OsB 2 is characterized by three different Fermi sheets, and we prove that this fermiology complies with recent quantum-oscillation experiments. Using the found microscopic properties, and experimental data from the literature, we employ Ginzburg-Landau relations to reveal that OsB 2 is a distinctly type-I superconductor with a very low Ginzburg-Landau parameter κ—a rare property among compound materials. We show that the found coherence length and penetration depth corroborate the measured thermodynamic critical field. Moreover, our calculation of the superconducting gap structure using anisotropic Eliashberg theory and ab initio calculated electron-phonon interaction as input reveals a single but anisotropic gap. The calculated gap spectrum is shown to give an excellent account for the unconventional behavior of the superfluid density of OsB 2 measured in experiments as a function of temperature. This reveals that gap anisotropy can explain such behavior, observed in several compounds, which was previously attributed solely to a two-gap nature of superconductivity.
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [1] ;  [1]
  1. Univ. of Antwerp, Antwerp (Belgium)
  2. Uppsala Univ., Uppsala (Sweden)
  3. Univ. of Antwerp, Antwerp (Belgium); Uppsala Univ., Uppsala (Sweden)
  4. Ames Lab. and Iowa State Univ., Ames, IA (United States)
Publication Date:
Report Number(s):
IS-J-9146
Journal ID: ISSN 2469-9950; PRBMDO
Grant/Contract Number:
MP1201; AC02-07CH11358
Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 94; Journal Issue: 14; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Research Org:
Ames Laboratory (AMES), Ames, IA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
OSTI Identifier:
1335027