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arXiv 1102.1911cond-mat.str-elcond-mat.supr-conphysics.comp-ph
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半满二维哈伯德模型中的超导性和成对涨落

Superconductivity and Pairing Fluctuations in the Half-Filled Two-Dimensional Hubbard Model

Michael Sentef, Philipp Werner, Emanuel Gull, Arno P. Kampf

摘要:

二维哈伯德模型在次近邻跳跃的存在下,即使在半填充时也表现出d波对称的超导性。利用元胞集团动力学平均场论和连续时间量子蒙特卡罗杂质求解器,我们揭示了超导态附近金属相的非费米液体性质。具体而言,低频散射率附近的动量(π,0)在低温下非单调变化,直流电导率是T-线性在升高的温度与冷却后的上升。证据表明,配对波动占主导地位的正常导电状态,甚至大大高于超导转变温度。

英文摘要:

The two-dimensional Hubbard model exhibits superconductivity with d-wave symmetry even at half-filling in the presence of next-nearest neighbor hopping. Using plaquette cluster dynamical mean-field theory with a continuous-time quantum Monte Carlo impurity solver, we reveal the non-Fermi liquid character of the metallic phase in proximity to the superconducting state. Specifically, the low-frequency scattering rate for momenta near (π, 0) varies non-monotonously at low temperatures, and the dc conductivity is T-linear at elevated temperatures with an upturn upon cooling. Evidence is provided that pairing fluctuations dominate the normal-conducting state even considerably above the superconducting transition temperature.

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