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Unified description of superconducting pairing symmetry in electron-doped Fe-based-122 compounds

Journal Article · · Physical Review. B, Condensed Matter and Materials Physics
 [1];  [2];  [3];  [3];  [3];  [1];  [1]
  1. Univ. of Houston, TX (United States). Dept. of Physics and Texas Center for Superconductivity
  2. Univ. of Houston, TX (United States). Dept. of Physics and Texas Center for Superconductivity; Yangzhou Univ. (China). School of Physics Science and Technology
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
+ Show Author Affiliations
Here, the pairing symmetry is examined in highly electron-doped Ba (Fe1-x Cox As)2 and Ay Fe2 Se2 (with A = K, Cs) compounds, with similar crystallographic and electronic band structures. Starting from a phenomenological two-orbital model, we consider nearest-neighbor and next-nearest-neighbor intraorbital pairing interactions on the Fe square lattice. In this model, we find a unified description of the evolution from s±-wave pairing (2.0 < n ≲ 2.4) to d-wave pairing (2.4 ≲ n ≲ 2.5) as a function of electron filling. In the crossover region, a time-reversal symmetry breaking s± + id pairing state emerges. This minimal model offers an overall picture of the evolution of superconductivity with electron doping for both s±-wave and d-wave pairings, as long as the dopants only play the role of a charge reservoir. However, the situation is more complicated for Ba (Fe1-x Cox As)2. A real-space study further shows that when the impurity scattering effects of Co dopants are taken into account, the superconductivity is completely suppressed for n > 2.4. This preempts any observation of d-wave pairing in this compound, in contrast to Ay Fe2 Se2 with 0.8 < y < 1.0.
Research Organization:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Organization:
National Science Foundation (NSF); Robert A. Welch Foundation; USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division
Grant/Contract Number:
AC52-06NA25396
OSTI ID:
1457233
Alternate ID(s):
OSTI ID: 1198527
Report Number(s):
LA-UR--15-22100
Journal Information:
Physical Review. B, Condensed Matter and Materials Physics, Journal Name: Physical Review. B, Condensed Matter and Materials Physics Journal Issue: 22 Vol. 91; ISSN 1098-0121; ISSN PRBMDO
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English

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Figures / Tables (2)

FIG. 1(p. 4)figure FIG. 1
FIG. 3(p. 6)figure FIG. 3

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