Non-trivial band topology in the superconductor AuSn₄: a first principle study

Abstract

Topological semimetals such as Weyl or Dirac semimetal with superconductivity have emerged as a new class of topological materials to realize and study Majorana Fermion in its intrinsic form. This article reports the Density Functional Theory (DFT) calculated bulk electronic band structure of recently discovered topological superconductor candidate Sn4Au. This study is further extended to the calculation of Z2 invariants. The Fermi surfaces corresponding to the bands which are responsible for non-trivial band topology along with the surface states are also mapped. The complete study suggests that Sn4Au is a topological semimetal. On Sn4Au, it is the first report in the literature showing the non-trivial band topology based on first-principle calculations.

Band structure, superconductivity, and polytypism in AuSn4

“…41 from powder x-ray diffraction. This might also explain the differences found in the determination of the lattice constants a and c (a, c ≈ 0.65 ± 0.01) in literature [17,18,20,23,24,66]. As we discuss below, here we show that the ARPES results are better explained by the No.…”

“…1(a)] were compatible with the crystal structure of AuSn 4 found previously. Note that here we find indistinguishable values for a and c from x-ray scattering, although literature reports provide small differences [17,[23][24][25]. Further details about the crystal structure, polytypism, and atomic positions are provided in Appendix A.…”

“…A recent examination of the bulk and transport properties of single crystals of AuSn 4 provides a clear specific heat jump at the superconducting transition. The proposed magnetic-field temperature phase diagram provides indications for twodimensional superconductivity in AuSn 4 [16][17][18].…”

“…41 noncentrosymmetric space group Aba2 [18,20,23,24,66]. Both present nearly identical lattice parameters, and the difference is purely coming from different heights of different peaks [17]. The powder x-ray diffraction is based on milling down the sample into ideally small grains of randomly distributed shapes.…”

“…PtSn 4 and PdSn 4 are not superconducting, * Corresponding author: edwin.herrera@uam.es but AuSn 4 is superconducting with a critical temperature of T c = 2.35 K [15]. The question if superconductivity in AuSn 4 is unconventional is important in the light of the anomalous band structure properties of PtSn 4 and PdSn 4 [16][17][18]. A recent examination of the bulk and transport properties of single crystals of AuSn 4 provides a clear specific heat jump at the superconducting transition.…”