Coherent interlayer coupling in quasi-two-dimensional Dirac fermions in $\alpha$-(BEDT-TTF)$_2$I$_3$

TL;DR

This paper demonstrates the presence of coherent interlayer coupling in $ ext{α}$-(BEDT-TTF)$_2$I$_3$, revealing a transition from two-dimensional to three-dimensional Dirac fermion behavior through combined theoretical and experimental analysis of resistivity under magnetic fields.

Contribution

It provides the first combined theoretical and experimental evidence of coherent interlayer tunneling in $ ext{α}$-(BEDT-TTF)$_2$I$_3$, estimating the tunneling magnitude and highlighting the transition to 3D electronic structure.

Findings

Peak in interlayer resistivity observed at low temperatures and high magnetic fields.

Estimated interlayer tunneling magnitude of approximately 1 meV.

Confirmation of three-dimensional Dirac fermion behavior in the material.

Abstract

Theoretical and experimental studies have supported that the electronic structure of $\alpha$-(BEDT-TTF)$_2$I$_3$ under pressure is described by two-dimensional Dirac fermions. When the interlayer tunneling is coherent, the electronic structure of the system becomes three-dimensional, and we expect the peak structure to appear in the interlayer resistivity under magnetic fields. We theoretically and experimentally show that the peak appears in the interlayer resistivity at low temperatures and high magnetic fields. From the experiment, we estimate that the magnitude of the interlayer tunneling is $t_1 \sim 1$ meV. Our result opens the door to investigating the three-dimensional electronic structure of $\alpha$-(BEDT-TTF)$_2$I$_3$.