Magnetic-Field Induced Semimetal in Topological Crystalline Insulator Thin Films

TL;DR

This paper explores how applying an in-plane magnetic field to a topological crystalline insulator thin film induces a transition to a semimetal with gapless cones, revealing a giant magnetoresistance effect.

Contribution

It demonstrates the magnetic-field induced semimetal phase in TCI thin films and analyzes the resulting electronic and electromagnetic properties, including the emergence of Weyl-like cones.

Findings

Magnetic field closes the gap and creates gapless cones with opposite chirality.

Perpendicular electric field shifts the gapless points and affects Fermi velocity.

The system exhibits giant magnetoresistance controlled by magnetic field.

Abstract

We investigate electromagnetic properties of a topological crystalline insulator (TCI) thin film under external electromagnetic fields. The TCI thin film is a topological insulator indexed by the mirror-Chern number. It is demonstrated that the gap closes together with the emergence of a pair of gapless cones carrying opposite chirarities by applying in-plane magnetic field. A pair of gapless points have opposite vortex numbers. This is a reminiscence of a pair of Weyl cones in 3D Weyl semimetal. We thus present an a magnetic-field induced semimetal-semiconductor transition in 2D material. This is a giant-magnetoresistance, where resistivity is controlled by magnetic field. Perpendicular electric field is found to shift the gapless points and also renormalize the Fermi velocity in the direction of the in-plane magnetic field.