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arXiv 0909.1625cond-mat.str-el
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团簇动力学平均场论中的光电导率:形式及其在高温超导体中的应用

Optical conductivity in cluster dynamical mean field theory: formalism and application to high temperature superconductors

Nan Lin, Emanuel Gull, A. J. Millis

摘要:

采用“动态团簇近似”方法,对高温铜氧化物超导体的动力学平均场论参数进行了计算,得到了单带哈伯德模型的光学电导率。计算中包括了顶点修正,计算结果表明了顶点修正的重要性。在每个站点的一个电子的密度,绝缘状态被发现与间隙值和间隙以上的吸收与测量一致。随着载流子的加入,上述间隙电导率迅速减弱,并出现三组分结构,具有低频“Drude”峰、中红外吸收和绝缘间隙的残余。在中间掺杂获得的中红外特征示出产生从赝能隙结构的状态密度。在进一步掺杂的电导率演变到德鲁德峰加上弱频率依赖性的尾部结构预期不太强相关的金属。

英文摘要:

The optical conductivity of the one-band Hubbard model is calculated using the 'Dynamical Cluster Approximation' implementation of dynamical mean field theory for parameters appropriate to high temperature copper-oxide superconductors. The calculation includes vertex corrections and the result demonstrates their importance. At densities of one electron per site, an insulating state is found with gap value and above-gap absorption consistent with measurements. As carriers are added the above gap conductivity rapidly weakens and a three component structure emerges, with a low frequency 'Drude' peak, a mid-infrared absorption, and a remnant of the insulating gap. The mid-infrared feature obtained at intermediate dopings is shown to arise from a pseudogap structure in the density of states. On further doping the conductivity evolves to the Drude peak plus weakly frequency dependent tail structure expected for less strongly correlated metals.

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