Low-energy electronic properties of Weyl semimetal quantum dot

TL;DR

This paper investigates the low-energy electronic properties of Weyl semimetal quantum dots, revealing surface and bulk states, their magnetic responses, and potential methods for experimental verification.

Contribution

It provides a simple model analysis of Weyl semimetal quantum dots, detailing surface state properties and their evolution under magnetic fields, aiding experimental identification.

Findings

Existence of surface and bulk states near Fermi level.

Surface states support persistent current and chiral spin polarization.

Surface states evolve into Landau levels under magnetic field.

Abstract

It is necessary to study the properties of Weyl semimetal nanostructures for potential applications in nanoelectronics. Here we study the Weyl semimetal quantum dot with a most simple model Hamiltonian with only two Weyl points. We focus on the low-energy electronic structure and show the correspondence to that of three-dimensional Weyl semimetal, such as Weyl point and Fermi arc. We find that there exist both surface and bulk states near Fermi level. The direct gap of bulk states reaches the minimum with the location determined by Weyl point. There exists a quantum number with only several values supporting surface states, which is the projection of Fermi arc. The property of surface state is studied in detail, including circular persistent current, orbital magnetic moment, and chiral spin polarization. Surface states will be broken by a strong magnetic field and evolve into Landau levels gradually. Simple expressions are derived to describe the energy spectra and electronic properties of surface states both in the presence and absence of magnetic field. In addition, this study may help design a method to verify Weyl semimetal by separating out the signal of surface states since quantum dot has the largest surface-to-volume ratio.