Competition between antiferromagnetic and charge order in the Hubbard-Holstein model
Competition between antiferromagnetic and charge order in the Hubbard-Holstein model
复制标题
哈伯德-荷尔斯泰因模型中反铁磁和电荷顺序之间的竞争
DOI：
10.1103/physrevb.81.235113
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发表时间：
2010
影响因子：
3.7
通讯作者：
A. Hewson
中科院分区：
文献类型：
--
作者：
J. Bauer;A. Hewson
我们研究了由Hubbard-Holstein模型描述的瞬时局域库仑排斥和玻色子介导的延迟吸引之间的竞争。在半填充情况下，分析了基态相图以及从反铁磁有序态到电荷有序态的跃迁。计算基于大维度的模型，从而可以应用动力学平均场理论，并使用数值重整化群方法来求解相关的杂质问题。当电子-电子耦合强度U与由电子-声子耦合引起的诱导相互作用近似重合时，发生跃迁。对于小的耦合和大的${\ensureath{\omega}_{0}$，我们发现了一个连续的转变，而对于大的耦合和/或小的${\ensureath{\omega}}_{0}$，我们发现了一个不连续的转变。我们给出了序参数、电子和声子的静态期望值以及相应的谱函数的结果。它们说明了在过渡附近可以看到的不同类型的行为。此外，在正常态下计算了准粒子的性质，这使得对低能激发的解释是一致的。
We study the competition between an instantaneous local Coulomb repulsion and a boson mediated retarded attraction, as described by the Hubbard-Holstein model. Restricting to the case of half-filling, the ground-state phase diagram and the transitions from antiferromagnetically ordered states to charge ordered states are analyzed. The calculations are based on the model in large dimensions, so that dynamical mean-field theory can be applied, and the associated impurity problem is solved using the numerical renormalization group method. The transition is found to occur when electron-electron coupling strength $U$ and the induced interaction $\ensuremath{\lambda}$ due to electron-phonon coupling approximately coincide, $U\ensuremath{\simeq}\ensuremath{\lambda}$. We find a continuous transition for small coupling and large ${\ensuremath{\omega}}_{0}$, and a discontinuous one for large coupling and/or small ${\ensuremath{\omega}}_{0}$. We present results for the order parameters, the static expectation values for the electrons and phonons, and the corresponding spectral functions. They illustrate the different types of behavior to be seen near the transitions. Additionally, the quasiparticle properties are calculated in the normal state, which leads to a consistent interpretation of the low-energy excitations.