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Possible Pairing Symmetry of BaPtAs$_{1-x}$Sb$_{x}$ with an Ordered Honeycomb Network

Tsuyoshi Imazu, Naoya Furutani, Tadashi Adachi, Kazutaka Kudo, Yoshiki Imai, Jun Goryo

Abstract

We investigate the possible pairing symmetry of superconducting $\rm{BaPtAs}_{1-\it{x}}\rm{Sb}_{\it{x}}$ solid solution with an ordered-honeycomb network of Pt and pnictogens. A spontaneous internal magnetic field below the superconducting transition temperature is observed in BaPtSb ($x = 1$) via the muon-spin relaxation measurement. We then pursue a scenario where the pairing symmetry is changed from a time-reversal symmetry-breaking (TRSB) state to another one by changing the Sb-concentration utilizing the effective tight-binding model obtained from the first principles calculations for $x = 0$ and $x = 1$, at which we see a significant difference in the shape of the dominant Fermi surfaces. We find that the chiral $d$-wave state with TRSB is most stable at $x = 1$, whereas the nodal $f$-wave or the conventional $s$-wave states without TRSB are competitive at $x = 0$.

Possible Pairing Symmetry of BaPtAs$_{1-x}$Sb$_{x}$ with an Ordered Honeycomb Network

Abstract

We investigate the possible pairing symmetry of superconducting solid solution with an ordered-honeycomb network of Pt and pnictogens. A spontaneous internal magnetic field below the superconducting transition temperature is observed in BaPtSb () via the muon-spin relaxation measurement. We then pursue a scenario where the pairing symmetry is changed from a time-reversal symmetry-breaking (TRSB) state to another one by changing the Sb-concentration utilizing the effective tight-binding model obtained from the first principles calculations for and , at which we see a significant difference in the shape of the dominant Fermi surfaces. We find that the chiral -wave state with TRSB is most stable at , whereas the nodal -wave or the conventional -wave states without TRSB are competitive at .
Paper Structure (5 sections, 7 equations, 7 figures, 2 tables)

This paper contains 5 sections, 7 equations, 7 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Electronic Structures and Effective Tight-binding Models
  3. Superconducting Hamiltonian and Gap Equations
  4. Phase Diagrams
  5. Conclusion

Figures (7)

  • Figure 1: (Color online) Crystal structures and properties of ordered honeycomb network superconductors Wenski-1986Kudo-jpsj-2018-BaPtAsNishikubo-jpsj-2011Kudo-jpsj-2018-BaPtSbBiswas-prb-2013Adachi-prb-2025. The crystal structures are visualized using VESTA Momma-jac-2011.
  • Figure 2: (Color online) The electronic band structures of (a) $\rm{BaPtAs}$ and (b) $\rm{BaPtSb}$. Red solid (black dashed) lines denote electronic band calculated with (without) SOC. Spin degeneracy is lifted by the ASOC. Insets show magnifications around the Fermi level near the M point (saddle point).
  • Figure 3: (Color online) DOS calculated without SOC around the Fermi level of (a) $\rm{BaPtAs}$ and (b) $\rm{BaPtSb}$.
  • Figure 4: (Color online) Fermi surfaces in 3D BZ and in 2D BZ for (left side) $\rm{BaPtAs}$ and (right side) $\rm{BaPtSb}$ visualized using Fermisurfer Kawamura-cp-2019. The center table shows the DOS of each Fermi surfaces that is estimated using tight-binding model mentioned in the text. The colour scale illustrates the magnitude of the Fermi velocity.
  • Figure 5: (Color online) Energy dispersion of effective tight-binding models of (a) $\rm{BaPtAs}$ and (b) $\rm{BaPtSb}$, and corresponding Fermi surfaces (c) $\rm{BaPtAs}$ and (d) $\rm{BaPtSb}$.
  • ...and 2 more figures