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arXiv 1406.6340cond-mat.str-el
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电荷、自旋和晶格自由度的相互作用对一维Hubbard-Holstein模型谱性质的影响

Interplay of charge, spin and lattice degrees of freedom on the spectral properties of the one-dimensional Hubbard-Holstein model

A. Nocera, M. Soltanieh-ha, C. A. Perroni, V. Cataudella, A. E. Feiguin

摘要:

我们利用含时密度矩阵重整化群(tDMRG)计算了一维Hubbard-Holstein模型的谱函数,着重于大的局域库仑排斥,而远离电子半填充.我们认为,从弱到中等的电子-声子耦合,声子只与电子电荷相互作用,而不是与自旋自由度。在强的电子-声子相互作用下,自旋和荷子带不再明显,系统可以用无自旋极化液体来描述。在这种情况下,我们观察到光谱中的多个峰,其能量分离对应于晶格振动的能量(即,声子)。我们支持的数值结果,通过引入一个良好的控制分析方法的基础上绪方Shiba的因式分解波函数,表明频谱可以被理解为卷积的三个贡献,来自电荷,自旋和晶格部门。我们认识和解释这些签名的光谱特性和讨论的实验意义。

英文摘要:

We calculate the spectral function of the one dimensional Hubbard-Holstein model using the time dependent Density Matrix Renormalization Group (tDMRG), focusing on the regime of large local Coulomb repulsion, and away from electronic half-filling. We argue that, from weak to intermediate electron-phonon coupling, phonons interact only with the electronic charge, and not with the spin degrees of freedom. For strong electron-phonon interaction, spinon and holon bands are not discernible anymore and the system is well described by a spinless polaronic liquid. In this regime, we observe multiple peaks in the spectrum with an energy separation corresponding to the energy of the lattice vibrations (i.e., phonons). We support the numerical results by introducing a well controlled analytical approach based on Ogata-Shiba's factorized wave-function, showing that the spectrum can be understood as a convolution of three contributions, originating from charge, spin, and lattice sectors. We recognize and interpret these signatures in the spectral properties and discuss the experimental implications.

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