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arXiv 1111.2939cond-mat.str-el
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t2g模型中的价键晶体和可能的轨道弹球液体

Valence Bond Crystal and possible orbital pinball liquid in a t2g model

Fabien Trousselet, Arnaud Ralko, Andrzej M. Oles

摘要:

我们研究了轨道简并莫特绝缘体的模型,其中局域电子具有t_2g自由度耦合的几个,竞争,交换机制。我们提供了两个不同的强烈波动制度的证据,这取决于是否超交换或直接交换机制占主导地位。在超交换为主的制度,基态是二聚化,最近邻轨道单线覆盖的晶格。通过推导出一个有效的量子二聚体模型,并对其进行数值分析,我们将此二聚相的特征描述为在一个大的晶胞内通过单线态共振稳定的价键晶体。在相反的制度,主要的直接交换,结合分析的原始模型和另一个有效的模型,适应当地的限制,表明subleading扰动选择一个高度共振的基态,与共存的对角和非对角远程轨道订单。

英文摘要:

We study a model for orbitally degenerate Mott insulators, where localized electrons possess t_2g degrees of freedom coupled by several, competing, exchange mechanisms. We provide evidence for two distinct strongly fluctuating regimes, depending on whether superexchange or direct exchange mechanism predominates. In the superexchange-dominated regime, the ground state is dimerized, with nearest neighbor orbital singlets covering the lattice. By deriving an effective quantum dimer model and analyzing it numerically, we characterize this dimerized phase as a valence bond crystal stabilized by singlet resonances within a large unit cell. In the opposite regime, with predominant direct exchange, the combined analysis of the original model and another effective model adapted to the local constraints, shows that subleading perturbations select a highly resonating ground state, with coexisting diagonal and off-diagonal long-range orbital orders.

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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