论文标题
压力下有机导体中二维狄拉克电子的异常电导率
Anomalous conductivity of two-dimensional Dirac electrons in organic conductor under pressures
论文作者
论文摘要
在压力下，已经使用二维紧密结合（TB）模型检查了有机导体电子中的电导率$α$ - （BEDT-TTF）$ _（BEDT-TTF）$ _ 2 $ _（BEDT-TTF）$ _ 2 $ _（bedt-ttf）$ _（bedt-ttf）$ _（bedt-ttf）$ _（bedt-ttf）$ _（bedt-ttf）$ _（bedt-ttf）。我们研究了电导率的异常温度依赖性，该温度依赖性在低温下[区域（i）]在高温下的$σ_{x} <σ_{y} $在低温下[region（i）]到$σ_{x}>σ_{y} $。 $σ_y$和$σ_x$分别平行于对角线电导率，分别垂直于分子的堆叠轴。狄拉克锥体倾斜的作用在区域（i）中占主导地位，而狄拉克锥体速度的各向异性在区域（II）中占主导地位。通过计算偏离分子电导率$σ_{xy} $以及由于E-P散射而在高温下近乎恒定的电导率而导致主轴的偏差进一步检查这种行为，这是简单两波段模型的先前结果的扩展。 Rev. b {\ bf 98}，161205（2018）]。讨论了与有机导体实验的相关性。
The electric conductivity of Dirac electrons in the organic conductor $α$-(BEDT-TTF)$_2$I$_3$ [BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene] under pressure has been examined using a two-dimensional tight-binding (TB) model with both impurity and electron--phonon (e--p) scatterings. We study an anomalous temperature dependence of the conductivity, which shows a crossover from $σ_{x} < σ_{y}$ at low temperatures [region (I)] to $σ_{x} > σ_{y}$ at high temperatures [region (II)]. $σ_y$ and $σ_x$ are diagonal conductivities parallel and perpendicular to a stacking axis of molecules, respectively. The effect of Dirac cone tilting is dominant in region (I), whereas the anisotropy of the velocity of the Dirac cone is dominant in region (II). Such behavior is further examined by calculating the deviation of principal axes due to the off-diagonal conductivity $σ_{xy}$ and a nearly constant conductivity at high temperatures due to the e--p scattering, which is the extension of the previous result of the simple two-band model [Phys. Rev. B {\bf 98},161205 (2018)]. The relevance to experiments of organic conductors is discussed.
