Pseudogaps in strongly correlated metals : Optical conductivity within the generalized dynamical mean-field theory approach
Pseudogaps in strongly correlated metals : Optical conductivity within the generalized dynamical mean-field theory approach
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强相关金属中的赝能隙：广义动态平均场理论方法中的光导率
DOI：
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发表时间：
2006
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影响因子：
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通讯作者：
M. V. Sadovskii
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文献类型：
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作者：
É. Z. Kuchinskii;I. Nekrasov;M. V. Sadovskii
利用广义动态平均场（DMFT+Sigma_p）方法计算了具有最近跳点和次最近跳点的方形晶格上弱掺杂二维排斥Hubbard模型的光学电导率，该方法通过动量依赖的自能Sigma_p将相关长度尺度xi纳入标准DMFT方程，并充分考虑了适当的顶点校正。该方法考虑了由短距离集体类sdw反铁磁自旋涨落引起的非局域动态关联，在足够高的温度下，可以将其视为具有有限关联长度xi的淬灭高斯随机场。利用数值重整化群（NRG）解决了有效单杂质问题。我们考虑了两种情况下的相关金属与带宽W b> W（局部哈伯德相互作用的U值）。在DMFT+Sigma_p中计算的光学电导率显示出准粒子带内典型的赝隙行为，与氧化铜超导体的实验结果定性一致。当U值较大时，赝隙异常被有效抑制。
Optical conductivity of the weakly doped two-dimensional repulsive Hubbard model on the square lattice with nearest and next nearest hoppings is calculated within the generalized dynamical-mean field (DMFT+Sigma_p) approach which includes correlation length scale xi into the standard DMFT equations via the momentum dependent self-energy Sigma_p, with full account of appropriate vertex corrections. This approach takes into consideration non-local dynamical correlations induced e.g. by short-ranged collective SDW-like antiferromagnetic spin fluctuations, which (at high enough temperatures) can be viewed as a quenched Gaussian random field with finite correlation length xi. The effective single impurity problem is solved by numerical renormalization group (NRG). We consider both the case of correlated metal with the bandwidth W >W (U - value of local Hubbard interaction). Optical conductivity calculated within DMFT+Sigma_p demonstrates typical pseudogap behavior within the quasiparticle band in qualitative agreement with experiments in copper oxide superconductors. For large values of U pseudogap anomalies are effectively suppressed.