Intervalley Tunneling and Crossover from the Positive to Negative Interlayer Magnetoresistance in Quasi-Two-Dimensional Dirac Fermion System with or without Mass Gap

TL;DR

This paper theoretically explores how interlayer magnetoresistance in quasi-2D Dirac fermion systems reveals whether fermions are massive, highlighting the role of intervalley tunneling and temperature effects in the crossover from positive to negative magnetoresistance.

Contribution

It introduces a method to determine the massiveness of Dirac fermions via interlayer magnetoresistance measurements, considering the effects of intervalley tunneling and temperature crossover.

Findings

Positive magnetoresistance arises from intervalley tunneling.

The interlayer magnetoresistance minimum indicates fermion massiveness.

The ratio of Fermi velocity to scattering rate can be extracted from crossover temperature.

Abstract

We theoretically investigate the interlayer magnetoresistance in quasi-two-dimensional Dirac fermion systems, where the Fermi energy is at the Dirac point. If there is an intermediate insulating layer that has an overlap with the wave functions in the Dirac fermion layers, there appears a positive magnetoresistance regime due to the intervalley tunneling. We show that the interlayer magnetoresistance can be used to find whether Dirac fermions are massive or not from the minimum in the interlayer magnetoresistance. As a specific system, we consider \alphaI under high pressure. We also discuss that one has to be careful in analyzing the crossover temperature from the positive to negative magnetoresistance. A simple picture is applied to the crossover in the zero temperature limit but it does not apply to the data at finite temperatures. We show that the ratio of the Fermi velocity to the scattering rate is evaluated from the zero temperature limit of the crossover temperature.