Tight-binding model with sublattice-asymmetric spin-orbit coupling for square-net nodal line Dirac semimetals

Nodal line semimetals in square net materials have been described with a two-site px-py tight binding model [1]. Although spin-orbit coupling (SOC) is introduced as an on-site perturbation in these models, to gap the zero-energy crossings it is also necessary that the two sublattices are inequivalent. In previous works, such asymmetry has been induced by atomic displacements or ad hoc on-site terms [2-4]. We followed a different approach: We developed a 16-orbital ab initio-based model for ZrSiS, and implemented Löwdin’s partitioning method to embed the effect of Zr on-site SOC into the minimal model constituted by Si’s px and py orbitals. In this way, we present a systematic method where the SOC-gaps in the px-py models emerge as a consequence of the hybridization of the bands.

References:

[1] S. Klemenz, L. Schoop, and J. Cano. Phys. Rev. B 101, 165121 (2020).

[2] W. Luo and H. Xiang. Nano Lett. 15, 3230 (2015).

[3] J. Deng, D. Shao, J. Gao, C. Yue, H. Weng, Z. Fang, and Z. Wang. Phys. Rev. B 105, 224103 (2022).

[4] N. Aryal, Q. Li, A. M. Tsvelik, and W. Yin. Phys. Rev. B 106, 235116 (2022).