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arXiv 1709.09461cond-mat.str-el
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Shastry-Sutherland晶格上哈伯德模型中几何阻挫对铁磁性的影响

Effects of geometrical frustration on ferromagnetism in the Hubbard model on the Shastry-Sutherland lattice

Pavol Farkasovsky

摘要:

采用小集团精确对角化计算和投影量子Monte Carlo方法研究了Shastry-Sutherland格点上哈伯德模型中几何阻挫和相互作用对铁磁性的竞争效应.它示出的几何挫折稳定的铁磁状态在高电子浓度($n \gtrsim 7/4$),其中铁磁性和非相互作用的状态密度的形状之间的强相关性被观察到。特别是,它被发现,铁磁性是稳定的,只有这些值的挫折参数,导致单峰noninterating态密度在带边。一旦非相互作用态密度在带边出现两个或多个峰,铁磁态被抑制。这为理解强关联系统中的铁磁性开辟了一条新的途径。

英文摘要:

The small-cluster exact-diagonalization calculations and the projector quantum Monte Carlo method are used to examine the competing effects of geometrical frustration and interaction on ferromagnetism in the Hubbard model on the Shastry-Sutherland lattice. It is shown that the geometrical frustration stabilizes the ferromagnetic state at high electron concentrations ($n \gtrsim 7/4$), where strong correlations between ferromagnetism and the shape of the noninteracting density of states are observed. In particular, it is found that ferromagnetism is stabilized only for these values of frustration parameters, which lead to the single peaked noninterating density of states at the band edge. Once, two or more peaks appear in the noninteracting density of states at the band egde the ferromagnetic state is suppressed. This opens a new route towards the understanding of ferromagnetism in strongly correlated systems.

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