Field-Tunable One-Sided Higher-Order Topological Hinge States in Dirac Semimetals

TL;DR

This paper proposes a method to realize and detect one-sided higher-order topological hinge states in Dirac semimetals like Cd$_3$As$_2$ using tilted magnetic fields, advancing understanding of 3D quantum Hall effects.

Contribution

It introduces a way to achieve and control one-sided hinge states in Dirac semimetals through magnetic field orientation and Fermi energy tuning, with a proposed detection method.

Findings

Tilted magnetic fields induce one-sided hinge states in Dirac semimetals.

Hinge states are tunable by field direction and Fermi energy.

Proposed scanning tunneling Hall measurement to detect hinge states.

Abstract

Recently, higher-order topological matter and 3D quantum Hall effects have attracted great attention. The Fermi-arc mechanism of the 3D quantum Hall effect proposed in Weyl semimetals is characterized by the one-sided hinge states, which do not exist in all the previous quantum Hall systems and more importantly pose a realistic example of the higher-order topological matter. The experimental effort so far is in the Dirac semimetal Cd$_3$As$_2$, where however time-reversal symmetry leads to hinge states on both sides of the top/bottom surfaces, instead of the aspired one-sided hinge states. We propose that under a tilted magnetic field, the hinge states in Cd$_3$As$_2$-like Dirac semimetals can be one-sided, highly tunable by field direction and Fermi energy, and robust against weak disorder. Furthermore, we propose a scanning tunneling Hall measurement to detect the one-sided hinge states. Our results will be insightful for exploring not only the quantum Hall effects beyond two dimensions, but also other higher-order topological insulators in the future.