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arXiv 1902.09053cond-mat.str-el
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富勒烯系超导体中的非常规轨道有序和涌现降维

Unconventional orbital ordering and emergent dimensional reduction in fulleride superconductors

Shintaro Hoshino, Philipp Werner, Ryotaro Arita

摘要:

提出了时空非定域序参量来表征富勒烯系超导体(Jahn-Teller金属)中非常规的轨道选择导电态。在以前的工作中,有人认为这种状态可以被解释为一个自发的轨道选择性的莫特态,其中两个$t_{1u}$分子轨道的电子是本地化的,而那些在第三个是金属。在这里,我们提供了一个系统的研究的非局部序参量和表征的Jahn-Teller金属,不存在一个单一的体局部序参量,在传统的有序的基础上的实际能带结构。它示出的Mottness,或整数填充性质的每个轨道由于强相关效应,是一个相关的功能,目前的轨道顺序。因此,局部轨道力矩消失,并且不存在与常规轨道力矩相关的静态失真。输运特性也进行了研究,并发现,有效地减少了维数从3到2在低能量,而在高能量的立方性质被恢复。这解释了在Jahn-Teller金属制度内的fcc富勒烯的超导态中观察到的高上临界场。

英文摘要:

Non-local order parameters in space-time are proposed to characterize the unconventional orbital-selective conducting state in fulleride superconductors, called the Jahn-Teller metal. In previous works, it has been argued that this state can be interpreted as a spontaneous orbital-selective Mott state, in which the electrons in two of the three $t_{1u}$ molecular orbitals are localized, while those in the third one are metallic. Here, based on the realistic band structure for fullerides, we provide a systematic study of nonlocal order parameters and characterize the Jahn-Teller metal, for which there exists no one-body local order parameter in contrast to conventional orderings. It is shown that the Mottness, or integer filling nature for each orbital due to strong correlation effects, is a relevant feature of the present orbital order. The local orbital moment thus vanishes and the static distortion associated with a conventional orbital moment is absent. Transport characteristics are also investigated, and it is found that the dimensionality is effectively reduced from three to two at low energies, while the cubic nature is recovered at high energies. This accounts for the high upper critical field observed in the superconducting state of the fcc fullerides inside the Jahn-Teller metal regime.

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