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arXiv 1101.2879cond-mat.str-el
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Peierls跃迁附近的动态电荷关联

Dynamic charge correlations near the Peierls transition

Martin Hohenadler, Holger Fehske, Fakher F. Assaad

摘要:

在一维无自旋Holstein模型的框架下,研究了排斥性Luttinger液体与绝缘Peierls态之间的量子相变.我们专注于绝热制度,但包括声子的全量子动力学。使用连续时间量子蒙特卡罗模拟,我们跟踪特别是动态电荷结构因子和单粒子光谱跨越过渡。随着电子-声子耦合的增加,动态电荷结构因子揭示了电荷间隙的出现,以及在带边界处声子软化的明显特征。单粒子谱函数在跃迁过程中不断演化。混合的电荷和声子模式的Luttinger液体描述导致两种模式,其中之一对应于相干极化子带。该带在进入Peierls相位时获得间隙,而另一模式构成具有折回阴影带的非相干高能光谱。相干极化子运动是量子晶格涨落的直接结果。在强耦合区,谱由静态平均场极限描述。重要的是,而有限的电子密度一般导致屏蔽极化子效应,后者重新出现在半填充由于电荷有序和晶格二聚。

英文摘要:

The quantum phase transition between a repulsive Luttinger liquid and an insulating Peierls state is studied in the framework of the one-dimensional spinless Holstein model. We focus on the adiabatic regime but include the full quantum dynamics of the phonons. Using continuous-time quantum Monte Carlo simulations, we track in particular the dynamic charge structure factor and the single-particle spectrum across the transition. With increasing electron-phonon coupling, the dynamic charge structure factor reveals the emergence of a charge gap, and a clear signature of phonon softening at the zone boundary. The single-particle spectral function evolves continuously across the transition. Hybridization of the charge and phonon modes of the Luttinger liquid description leads to two modes, one of which corresponds to the coherent polaron band. This band acquires a gap upon entering the Peierls phase, whereas the other mode constitutes the incoherent, high-energy spectrum with backfolded shadow bands. Coherent polaronic motion is a direct consequence of quantum lattice fluctuations. In the strong-coupling regime, the spectrum is described by the static, mean-field limit. Importantly, whereas finite electron density in general leads to screening of polaron effects, the latter reappear at half filling due to charge ordering and lattice dimerization.

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