A new class of bilayer kagome lattice compounds with Dirac nodal lines and pressure-induced superconductivity

TL;DR

This paper introduces a new family of vanadium-based kagome compounds with Dirac nodal lines near the Fermi level, and reports pressure-induced superconductivity, opening avenues for exploring topological and collective phenomena.

Contribution

It reports the discovery and characterization of a new class of vanadium-based kagome compounds with Dirac nodal lines and pressure-induced superconductivity, expanding the family of topologically interesting kagome materials.

Findings

Presence of Dirac nodal lines near the Fermi level

Pressure induces superconductivity in $A$V$_6$Sb$_6$ compounds

New layered kagome materials with diverse topological properties

Abstract

Kagome lattice composed of transition-metal ions provides a great opportunity to explore the intertwining between geometry, electronic orders and band topology. The discovery of multiple competing orders that connect intimately with the underlying topological band structure in nonmagnetic kagome metals $A$V$_3$Sb$_5$ ($A$ = K, Rb, Cs) further pushes this topic to the quantum frontier. Here we report the discovery and characterization of a new class of vanadium-based compounds with kagome bilayers, namely $A$V$_6$Sb$_6$ ($A$ = K, Rb, Cs) and V$_6$Sb$_4$, which, together with $A$V$_3$Sb$_5$, compose a series of kagome compounds with a generic chemical formula ($A_{m-1}$Sb$_{2m}$)(V$_3$Sb)$_n$ (m = 1, 2; n = 1, 2). Theoretical calculations combined with angle-resolved photoemission measurements reveal that these compounds feature Dirac nodal lines in close vicinity to the Fermi level. Pressure-induced superconductivity in $A$V$_6$Sb$_6$ further suggests promising emergent phenomena in these materials. The establishment of a new family of layered kagome materials paves the way for designer of fascinating kagome systems with diverse topological nontrivialities and collective ground states.