Unusual magneto-transport from Si-square nets in topological semimetal HfSiS

TL;DR

This study investigates the topological properties and magnetotransport behavior of HfSiS, revealing nontrivial Berry phase, complex Fermi surface topology, and anisotropic magnetoresistance linked to its nodal line semimetal nature.

Contribution

It provides the first detailed experimental analysis of the Berry phase, Fermi surface topology, and magnetoresistance in HfSiS, confirming its status as a nodal line semimetal with unique electronic features.

Findings

Nontrivial pi-Berry phase observed, indicating topological Dirac dispersion.

3D Fermi surface with asymmetric electron and hole pockets characterized.

Anisotropic magnetoresistance linked to Fermi surface topology and band structure.

Abstract

The class of topological semimetals comprises a large pool of compounds. Together they provide a wide platform to realize exotic quasiparticles for example Dirac, nodal line Dirac and Weyl fermions. In this letter, we report the Berry phase, Fermi surface topology and anisotropic magnetoresistance of HfSiS which has recently been predicted to be a nodal line semimetal. This compound contains large carrier density, higher than most of the known semimetals. Massive amplitudes of de Haas-van Alphen and Shubnikov-de Haas oscillations up to 20 K in 7 T assist us in witnessing nontrivial pi-Berry phase which is a consequence of topological Dirac-type dispersion of bands originating from the hybridization of px + py and dx2-y2 orbitals of square-net plane of Si and Hf atoms, respectively. Furthermore, we establish the 3D Fermi-surface which consists of very asymmetric water caltrop-like electron and barley seed-like hole pockets which account for the anisotropic magnetoresistance in HfSiS.