# Negative Magnetoresistance without Chiral Anomaly in Topological Insulators

## TL;DR

This paper explains the negative magnetoresistance observed in topological insulators through Berry curvature effects, without relying on the chiral anomaly, and matches experimental data.

## Contribution

It provides a theoretical model using semiclassical equations that accounts for negative MR in topological insulators, highlighting the roles of Berry curvature, orbital moment, and g factors.

## Key findings

- Negative MR is insensitive to temperature.
- Negative MR increases as Fermi energy approaches the band edge.
- Orbital moment and g factors significantly influence negative MR.

## Abstract

An intriguing phenomenon in topological semimetals and topological insulators is the negative magnetoresistance (MR) observed when a magnetic field is applied along the current direction. A prevailing understanding to the negative MR in topological semimetals is the chiral anomaly, which, however, is not well defined in topological insulators. We calculate the MR of a three-dimensional topological insulator, by using the semiclassical equations of motion, in which the Berry curvature explicitly induces an anomalous velocity and orbital moment. Our theoretical results are in quantitative agreement with the experiments. The negative MR is not sensitive to temperature and increases as the Fermi energy approaches the band edge. The orbital moment and g factors also play important roles in the negative MR. Our results give a reasonable explanation to the negative MR in 3D topological insulators and will be helpful in understanding the anomalous quantum transport in topological states of matter.