First-Principles Study of Electronic Structure in $\alpha$-(BEDT-TTF)$_2$I$_3$ at Ambient Pressure and with Uniaxial Strain

TL;DR

This study uses density functional theory to analyze how uniaxial strain affects the electronic structure of $ ext{(BEDT-TTF)}_2 ext{I}_3$, revealing anisotropic Dirac cones and temperature-dependent carrier densities.

Contribution

It provides a detailed first-principles analysis of strain effects on the electronic properties of $ ext{(BEDT-TTF)}_2 ext{I}_3$, including tight-binding parameter extraction and temperature behavior.

Findings

Confirmation of anisotropic Dirac cone dispersion near the chemical potential.

Distinct effects of uniaxial strain along the a- and b-axes.

Carrier densities exhibit $T^2$ dependence at low temperatures.

Abstract

Within the framework of the density functional theory, we calculate the electronic structure of $\alpha$-(BEDT-TTF)$_2$I$_3$ at 8K and room temperature at ambient pressure and with uniaxial strain along the $a$- and $b$-axes. We confirm the existence of anisotropic Dirac cone dispersion near the chemical potential. We also extract the orthogonal tight-binding parameters to analyze physical properties. An investigation of the electronic structure near the chemical potential clarifies that effects of uniaxial strain along the a-axis is different from that along the b-axis. The carrier densities show $T^2$ dependence at low temperatures, which may explain the experimental findings not only qualitatively but also quantitatively.