Berry Phase of Dirac Nodal Line Semimetal in Single-Component Molecular Conductor

TL;DR

This paper investigates the Berry phase and curvature in a Dirac nodal line semimetal within a single-component molecular conductor, revealing the topological properties and potential experimental implications.

Contribution

It introduces a two-band tight-binding model to calculate the Berry phase and curvature along the nodal line, providing new insights into the topological characteristics of this material.

Findings

Berry curvature exists along the nodal line loop

Berry (Zak) phase is calculated from surface and line integrals

Discussion of experimental detection of the Berry phase

Abstract

The Berry phase and curvature are studied for the Dirac nodal line semimetal of single-component molecular conductor [Pd(dddt)$_2$]. Using two-band model on the basis of a tight-binding model, it is shown that the Berry curvature, $\bm{B}(\bm{k})$, exists along a loop of the nodal line, on which the Berry phase is obtained from surface integral of $\bm{B}(\bm{k})$. The Berry phase, which is called Zak phase, is also calculated from one-dimensional integral of the Berry connection along a line between two equivalent points of boundaries of Brillouin zone. The possible experiment is discussed in terms of the Berry phase.