Universal Behavior of Magnetoresistance in Organic Dirac Electron Systems

TL;DR

This study reveals a universal in-plane magnetoresistance behavior in organic Dirac electron systems under low magnetic fields, regardless of their gapped or gapless states, suggesting a fundamental property of these materials.

Contribution

It demonstrates the universal magnetoresistance behavior across multiple organic Dirac electron systems under pressure, including gapped states, expanding understanding of their electronic properties.

Findings

Universal magnetoresistance observed in various organic Dirac systems.

Behavior persists even in gapped states under certain conditions.

Magnetoresistance depends on temperature, magnetic field, and orientation.

Abstract

In-plane magnetoresistance for organic massless Dirac electron system (OMDES) $\alpha$-(BEDT-TTF)$_2$I$_3$ and $\theta$-(BEDT-TTF)$_2$I$_3$ in addition to possible candidates of the OMDES $\alpha$-(BETS)$_2$I$_3$ and $\alpha$-(BEDT-STF)$_2$I$_3$, was investigated under hydrostatic pressure. We have found the universal behavior of the in-plane magnetoresistance under a low magnetic field perpendicular to two-dimensional plane. As for $\alpha$-(BEDT-TTF)$_2$I$_3$, the universality was examined with the parameters of temperature, magnetic field and its direction. We suggest that the universal magnetoresistance behavior is found even for the gapped state of $\alpha$-(BEDT-TTF)$_2$I$_3$ under intermediate pressure, when the thermal energy exceeds the gap.