Electric Conductivity of the Zero−Gap Semiconducting State in <TEX>$\alpha$</TEX>−(BEDT−TTF)2I3 Salt

概要

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Electric conductivity that reveals the zero−gap semiconducting (ZGS) state has been investigated as a function of temperature <TEX>$T$</TEX> and lifetime <TEX>$\tau$</TEX> in order to understand the ZGS state in a quarter−filled <TEX>$\alpha$</TEX>−(BEDT−TTF)2I3 salt with four sites in the unit cell. By treating <TEX>$\tau$</TEX> as a parameter and employing the one−loop approximation, it is found that the conductivity is proportional to <TEX>$T$</TEX> and <TEX>$\tau$</TEX> for <TEX>$k_{\text{B}} T\gg\hbar/\tau$</TEX> and is independent of <TEX>$T$</TEX> and <TEX>$\tau$</TEX> for <TEX>$k_{\text{B}} T\ll\hbar/\tau$</TEX>. Further, the conductivity, which is independent of <TEX>$T$</TEX> in the ZGS state, is examined for the impurity scattering in terms of the Born approximation.
2006-02-15