# Interlayer quantum transport in Dirac semimetal BaGa$_2$

## TL;DR

This study investigates the interlayer quantum transport in the multilayered Dirac semimetal BaGa$_2$, revealing negative magnetoresistance and angle-dependent resistivity peaks due to Dirac fermion tunneling in the quantum limit.

## Contribution

It provides the first experimental observation of negative interlayer magnetoresistance and resistivity peaks in Dirac semimetals under ambient conditions, explained by tunneling of Dirac fermions.

## Key findings

- Negative interlayer magnetoresistance observed.
- Resistivity peaks when magnetic field is perpendicular to c-axis.
- Transport properties explained by Dirac fermion tunneling model.

## Abstract

Quantum limit is quite easy to achieve once the band crossing exists exactly at the Fermi level ($E_F$) in topological semimetals. In multilayered Dirac fermion system, the density of Dirac fermions on the zeroth Landau levels (LLs) increases in proportion to the magnetic field, resulting in intriguing angle- and field-dependent interlayer tunneling conductivity near the quantum limit. BaGa$_2$ is an example of multilayered Dirac semimetal with anisotropic Dirac cone close to $E_F$, providing a good platform to study its interlayer transport properties. In this paper, we report the negative interlayer magnetoresistance (NIMR, I//c and B//c) induced by the tunneling of Dirac fermions on the zeroth LLs of neighbouring Ga layers in BaGa$_2$. When the field deviates from the c-axis, the interlayer resistivity $\rho_{zz}(\theta)$ increases and finally results in a peak with the field perpendicular to the c-axis. These unusual interlayer transport properties (NIMR and resistivity peak with B$\perp$c) are observed together for the first time in Dirac semimetal under ambient pressure and are well explained by the model of tunneling between Dirac fermions in the quantum limit.