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arXiv 1104.0109cond-mat.str-elquant-ph
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长程关联对正方格子上哈伯德模型非磁Mott相变的影响

Effects of Long-Range Correlations on Nonmagnetic Mott Transitions in Hubbard model on Square Lattice

Tomoaki Miyagawa, Hisatoshi Yokoyama

摘要:

本文用变分Monte Carlo方法研究了正方晶格上哈伯德模型的Mott跃迁机制,并没有明确地引入磁关联和超导关联。在试验波函数中,我们考虑了双占据位置(doublon,D)和空位置(holon,H)之间的各种类型的结合因子,如长程类型以及传统的最近邻类型,并添加独立的长程D-D(H-H)因子。研究发现,D-H结合因子的选择范围较宽时,在谱带宽度附近的临界值处发生Mott跃迁。我们通过引入两个特征长度尺度,即D-H结合长度l_{DH}和最小D-D距离l_{DD},更新了Mott跃迁的D-H结合图,并对这两个尺度进行了适当的估计.莫特跃迁发生在l_{DH} = l_{DD}。在金属状态(l_{DH} > l_{DD})中,D-H对的结构域彼此重叠,因此双链子和holon可以通过一个接一个地交换配偶体而独立移动。相比之下,D-D因子对Mott转变的贡献很小。

英文摘要:

The mechanism of Mott transition in the Hubbard model on the square lattice is studied without explicit introduction of magnetic and superconducting correlations, using a variational Monte Carlo method. In the trial wave functions, we consider various types of binding factors between a doubly-occupied site (doublon, D) and an empty site (holon, H), like a long-range type as well as a conventional nearest-neighbor type, and add independent long-range D-D (H-H) factors. It is found that a wide choice of D-H binding factor leads to Mott transitions at critical values near the band width. We renew the D-H binding picture of Mott transitions by introducing two characteristic length scales, the D-H binding length l_{DH} and the minimum D-D distance l_{DD}, which we appropriately estimate. A Mott transition takes place at l_{DH}=l_{DD}. In the metallic regime (l_{DH}>l_{DD}), the domains of D-H pairs overlap with one another, thereby doublons and holons can move independently by exchanging the partners one after another. In contrast, the D-D factors give only a minor contribution to the Mott transition.

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。

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