arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0705.0581cond-mat.str-el
收藏

二维掺杂哈伯德模型的非局域激发谱

Nonlocal Excitation Spectra in 2D Doped Hubbard Model

Yoshiro Kakehashi, Peter Fulde

摘要:

利用自洽投影算符方法研究了零温下正方形晶格上二维哈伯德模型的单粒子激发谱。该方法保证了高能量和高动量分辨率的光谱的高精度。它既考虑了站点间的长距离相关性,也考虑了站点内的强相关性。通过与单点近似的结果进行比较,阐明了非局部激发的影响。计算的光谱验证了有限温度下的量子Monte-Carlo结果。费米能级的光谱在欠掺杂区产生类空穴费米面,在过掺杂区产生类电子费米面。从动量相关的有效质量和自能的数值分析,它的结论是,边缘费米液体的状态持续存在,即使在有限的掺杂浓度在强关联区域,因为范霍夫奇点钉在费米表面。同时还发现在同一区域的准粒子能带中出现了扭结结构。扭结被证明是由准粒子带和激发带之间的混合与强短程反铁磁相关。这些结果表明,在高$T_{\rm c}$铜酸盐的正常状态的一些不寻常的属性的解释。

英文摘要:

Single-particle excitation spectra of the two-dimensional Hubbard model on the square lattice near half filling and at zero temperature are investigated on the basis of the self-consistent projection operator method. The method guarantees a high accuracy of the spectra with high energy and high momentum resolutions. It takes into account long-range intersite correlations as well as the strong on-site correlations. Effects of nonlocal excitations are clarified by comparing the results with those of the single-site approximation. The calculated spectra verify the quantum Monte-Carlo results for finite temperatures. The spectra at the Fermi level yield a hole-like Fermi surface in the underdoped region and an electron-like Fermi surface in the overdoped region. From a numerical analysis of the momentum dependent effective mass and self-energy, it is concluded that a marginal Fermi-liquid like state persists even at finite doping concentrations in the strongly correlated region because a van Hove singularity is pinned to the Fermi surface. It is also found that a kink structure appears in the quasiparticle energy band in the same region. The kink is shown to be caused by a mixing between the quasiparticle band and an excitation band with strong short-range antiferromagnetic correlations. These results suggest an explanation for some of the unusual properties of the normal state in high-$T_{\rm c}$ cuprates.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑