Binary kagome superconducting candidates hosting topological electronic states

Abstract

Topological superconductivity has attracted broad interest because of its connection to Majorana fermions and quantum computation. Kagome materials provide a natural setting in which interesting electronic structures, topological surface states, and superconductivity may occur in nearby energy windows. Here we carry out a systematic first-principles search for binary kagome superconducting candidates with topological electronic states across several structural families $A_mB_n$ ($m$:$n$=3:1; 3:2; 1:1). The screening combines formation-energy and phonon-stability filtering, magnetic-ground-state searches, electron-phonon-coupling calculations, and topological electronic-structure analysis. We identify 286 nonmagnetic dynamically stable candidates for electron-phonon-coupling analysis, among which 84 have estimated transition temperatures above 3 K and seven exceed the $\sim 9$ K reference scale of existing ambient-pressure kagome superconductors. In addition, several systems are predicted to host abundant topological surface states near the Fermi level. NbBi is identified as a $\mathbb{Z}_2$ topological metal with clear Dirac-cone topological surface states and a kagome-derived flat band near $E_F$. Ti$_3$Si, with the largest estimated $T_\text{c}=15.2$ K in this dataset, shows nodal-line-derived drumhead surface states and selected nodes that survive spin-orbit coupling near $E_F$. Combining superconductivity with nontrivial topological electronic structures, the binary kagome compounds predicted here represent compact and chemically tunable candidate platforms for topological superconductivity and for exploring kagome-related quantum phenomena.