Quantum oscillations revealing topological band in kagome metal ScV6Sn6

TL;DR

This study uncovers topological Dirac bands in kagome metal ScV6Sn6 through quantum oscillations, revealing complex Fermi surface topology and Berry phase effects, with implications for quantum phenomena in this material.

Contribution

It provides the first experimental evidence of topological Dirac bands and Fermi surface topology in ScV6Sn6 using quantum oscillations and theoretical calculations.

Findings

Presence of Dirac band with non-zero Berry phase

Multiple small Fermi surfaces identified

Anomalous Hall-like behavior observed

Abstract

Compounds with kagome lattice structure are known to exhibit Dirac cones, flat bands, and van Hove singularities, which host numerous versatile quantum phenomena. Inspired by these intriguing properties, we investigate the temperature and magnetic field dependent electrical transports along with the theoretical calculations of ScV6Sn6, a nonmagnetic charge density wave (CDW) compound. At low temperatures, the compound exhibits Shubnikov-de Haas quantum oscillations, which help to design the Fermi surface (FS) topology. This analysis reveals the existence of several small FSs in the Brillouin zone, combined with a large FS. Among them, the FS possessing Dirac band is a non-trivial and generates a non-zero Berry phase. In addition, the compound also shows the anomalous Hall-like behaviour up to the CDW with the CDW phase, ScV6Sn6 presents a unique material example of the versatile HfFe6Ge6 family and provides various promising opportunities to explore the series further.