Electric Conductivity of the Zero-gap Semiconducting State in Alpha-(BEDT-TTF)2I3 Salt

TL;DR

This study investigates the electric conductivity behavior of the zero-gap semiconducting state in alpha-(BEDT-TTF)2I3 salt, revealing temperature and lifetime dependencies and the conditions under which conductivity remains temperature-independent.

Contribution

It provides a theoretical analysis of conductivity in the ZGS state of alpha-(BEDT-TTF)2I3, highlighting the effects of temperature, lifetime, and impurity scattering.

Findings

Conductivity is proportional to T and τ when k_B >> ħ/τ.

Conductivity becomes independent of T and τ when k_B T << ħ/τ.

Conductivity remains temperature-independent in the ZGS state under impurity scattering.

Abstract

The electric conductivity which reveals the zero gap semiconducting (ZGS) state has been investigated as the function of temperature $T$ and life time $\tau$ in order to understand the ZGS state in quarter-filled $\alpha$-(BEDT-TTF)$_2$I$_3$ salt with four sites in the unit cell. By treating $\tau$ as a parameter and making use of the one-loop approximation, it is found that the conductivity is proportional to $T$ and $\tau$ for $k_B\gg\hbar/\tau$ and independent of $T$ and $\tau$ for $k_B T\ll\hbar/\tau$. Further the conductivity being independent of $T$ in the ZGS state is examined in terms of Born approximation for the impurity cattering.