Topological superconductivity and large spin Hall effect in the kagome family Ti6X4 (X = Bi, Sb, Pb, Tl, and In)

Xin-Wei Yi; Zheng-Wei Liao; Jing-Yang You; Bo Gu; Gang Su

doi:10.1016/j.isci.2022.105813

Topological superconductivity and large spin Hall effect in the kagome family Ti₆X₄ (X = Bi, Sb, Pb, Tl, and In)

iScience. 2022 Dec 17;26(1):105813. doi: 10.1016/j.isci.2022.105813. eCollection 2023 Jan 20.

Authors

Xin-Wei Yi¹, Zheng-Wei Liao¹, Jing-Yang You², Bo Gu^{1

3}, Gang Su^{1

3}

Affiliations

¹ School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
² Department of Physics, Faculty of Science, National University of Singapore, Singapore 117551, Singapore.
³ Kavli Institute for Theoretical Sciences, CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China.

Abstract

Topological superconductors (TSC) become a focus of research due to the accompanying Majorana fermions. However, the reported TSC are extremely rare. Recent experiments reported kagome TSC AV₃Sb₅ (A = K, Rb, and Cs) exhibit unique superconductivity, topological surface states (TSS), and Majorana bound states. More recently, the first titanium-based kagome superconductor CsTi₃Bi₅ with nontrivial topology was successfully synthesized as a perspective TSC. Given that Cs contributes little to electronic structures of CsTi₃Bi₅ and binary compounds may be easier to be synthesized, here, by first-principle calculations, we predict five stable nonmagnetic kagome compounds Ti₆X₄ (X = Bi, Sb, Pb, Tl, and In) which exhibit superconductivity with critical temperature Tc = 3.8 K $-$ 5.1 K, nontrivial $Z_{2}$ band topology, and TSS close to the Fermi level. Additionally, large intrinsic spin Hall effect is obtained in Ti₆X₄, which is caused by gapped Dirac nodal lines due to a strong spin-orbit coupling. This work offers new platforms for TSC and spintronic devices.

Keywords: Condensed matter physics; Physics; Superconductivity.