The de Hass-van Alphen quantum oscillations in BaSn3 superconductor with multiple Dirac fermions

TL;DR

This study investigates the electronic structure and quantum oscillations in BaSn3 superconductor, revealing the presence of multiple Dirac fermions and nontrivial Berry phases, highlighting its potential for exploring topological superconductivity.

Contribution

The paper combines experimental dHvA measurements with ab initio calculations to identify multiple Dirac points and topological features in BaSn3, a superconductor.

Findings

Observation of nontrivial Berry phase in quantum oscillations.

Identification of two type-II Dirac points near the Fermi level.

Support for BaSn3 as a platform for topological and superconducting studies.

Abstract

By measuring the de Hass-van Alphen effect and calculating the electronic band structure, we have investigated the bulk Fermi surface of the BaSn3 superconductor with a transition temperature of ~ 4.4 K. Striking de Haas-van Alphen (dHvA) quantum oscillations are observed when the magnetic field B is perpendicular to both (100) and (001) planes. Our analysis unveiled nontrivial Berry phase imposed in the quantum oscillations when B is perpendicular to (100), with two fundamental frequencies at 31.5 T and 306.7 T, which likely arise from two corresponding hole pockets of the bands forming a type-II Dirac point. The results are supported by the ab initio calculations indicating a type-II Dirac point setting and tilting along the high symmetric K-H line of the Brillouin zone, about 0.13 eV above the Fermi level. Moreover, the calculations also revealed other two type-I Dirac points on the high symmetric {\Gamma}-A direction, but slightly far below the Fermi level. The results demonstrate BaSn3 as an excellent platform for the study of not only exotic properties of different types of Dirac fermions in a single material, but also the interplay between nontrivial topological states and superconductivity.