Crossover from Positive to Negative Interlayer Magnetoresistance in Multilayer Massless Dirac Fermion System with Non-Vertical Interlayer Tunneling

TL;DR

This paper theoretically investigates how interlayer magnetoresistance in layered Dirac fermion systems transitions from negative to positive due to non-vertical tunneling and Landau level effects, providing insights into the energy spectrum.

Contribution

It introduces a theoretical model explaining the crossover in interlayer magnetoresistance, emphasizing the role of non-vertical tunneling and Landau level mixing.

Findings

Crossover magnetic field depends on Landau level broadening.

Negative magnetoresistance linked to zero-energy Landau level.

Positive magnetoresistance arises from Landau level mixing.

Abstract

We present a theoretical description of the interlayer magnetoresistance in the layered Dirac fermion system with the application to the organic conductor \alpha-(BEDT-TTF)_2I_3 under pressure. Assuming a non-vertical interlayer tunneling and including higher Landau level effects we calculate the interlayer conductivity using the Kubo formula.We propose a physical picture of the experimentally observed crossover from the negative interlayer magnetoresistance, where the Dirac fermion zero-energy Landau level plays a central role, to the positive interlayer magnetoresistance that is the consequence of the Landau level mixing effect upon non-vertical interlayer hopping. The crossover magnetic field depends on the Landau level broadening factor and can be used to determine the Dirac fermion Landau level energy spectrum.