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arXiv 1504.07641cond-mat.str-el
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具有节环谱的三维半金属中的朗道能级量子化和几乎平坦模

Landau Level Quantization and Almost Flat Modes in Three-dimensional Semi-metals with Nodal Ring Spectra

Jun-Won Rhim, Yong Baek Kim

摘要:

研究了节环色散半金属的朗道能级结构。当磁场平行于环所在平面时,在费米能级(E_F = 0)处存在几乎无色散的朗道能级,它是环内沿磁场方向动量的函数。我们发现,朗道能级在每个动量沿磁场方向可以描述的哈密顿量的石墨烯双层与虚构的层间耦合下倾斜的磁场。在环的中心附近,层间耦合可以忽略不计,我们有狄拉克朗道能级,解释了零模的出现。虽然层间跳跃振幅在较高的动量变得有限,零模式的分裂是指数小,它们几乎保持平坦,由于有限的人工面内分量的磁场。费米能级处态密度峰值的出现是环色散的标志。

英文摘要:

We investigate novel Landau level structures of semi-metals with nodal ring dispersions. When the magnetic field is applied parallel to the plane in which the ring lies, there exist almost non-dispersive Landau levels at the Fermi level (E_F = 0) as a function of the momentum along the field direction inside the ring. We show that the Landau levels at each momentum along the field direction can be described by the Hamiltonian for the graphene bilayer with fictitious inter-layer couplings under a tilted magnetic field. Near the center of the ring where the inter-layer coupling is negligible, we have Dirac Landau levels which explain the appearance of the zero modes. Although the inter-layer hopping amplitudes become finite at higher momenta, the splitting of zero modes is exponentially small and they remain almost flat due to the finite artificial in-plane component of the magnetic field. The emergence of the density of states peak at the Fermi level would be a hallmark of the ring dispersion.

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