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arXiv 1707.03085cond-mat.str-el
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NbO $_2$与VO $_2$的动态电子相关效应比较

Dynamic electronic correlation effects in NbO$_2$ as compared to VO$_2$

W. H. Brito, M. C. O. Aguiar, K. Haule, G. Kotliar

摘要:

在这项工作中,我们提出了一个比较调查的电子结构的NbO $_2$和VO $_2$内得到的结合密度泛函理论和集群动力学平均场论计算。我们研究了动态电子关联对NbO $_2$和VO $_2$金属相和绝缘相电子结构的影响,重点研究了绝缘相能隙开放的机制.对于两种氧化物的金红石金属相,我们得到的电子相关性导致强重整化的$t_{2g}$子带,以及出现不相干的哈伯德子带,信号电子相关性也很重要的金属相的NbO $_2$。有趣的是,我们发现,非局部动力学关联发挥作用的间隙形成的(bct)绝缘相的NbO $_2$,由一个类似的物理机制,我们最近提出的情况下的(M $_1$)二聚相VO $_2$(\textit{Phys. Rev. Lett. 117, 056402 (2016)})。虽然bct相的间隙开放的非局部动力学相关性的影响是不太重要的比在(M $_1$和M $_2$)单斜相VO $_2$,他们的存在表明,前者不是一个纯粹的Peierls型绝缘体,因为它是最近提出的。

英文摘要:

In this work we present a comparative investigation of the electronic structures of NbO$_2$ and VO$_2$ obtained within the combination of density functional theory and cluster-dynamical mean field theory calculations. We investigate the role of dynamic electronic correlations on the electronic structure of the metallic and insulating phases of NbO$_2$ and VO$_2$, with focus on the mechanism responsible for the gap opening in the insulating phases. For the rutile metallic phases of both oxides, we obtain that electronic correlations lead to strong renormalization of the $t_{2g}$ subbands, as well as the emergence of incoherent Hubbard subbands, signaling that electronic correlations are also important in the metallic phase of NbO$_2$. Interestingly, we find that nonlocal dynamic correlations do play a role in the gap formation of the (bct) insulating phase of NbO$_2$, by a similar physical mechanism as that recently proposed by us in the case of the (M$_1$) dimerized phase of VO$_2$ (\textit{Phys. Rev. Lett. 117, 056402 (2016)}). Although the effect of nonlocal dynamic correlations in the gap opening of bct phase is less important than in the (M$_1$ and M$_2$) monoclinic phases of VO$_2$, their presence indicates that the former is not a purely Peierls-type insulator, as it was recently proposed.

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