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arXiv 2008.04326cond-mat.mes-hall
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拓扑Lifshitz跃迁附近半Dirac费米子的库仑相互作用和重整化

Coulomb interactions and renormalization of semi-Dirac fermions near a topological Lifshitz transition

Valeri N. Kotov, Bruno Uchoa, Oleg P. Sushkov

摘要:

我们的目标是了解如何的光谱半狄拉克费米子重整化由于长程库仑电子-电子相互作用在拓扑Lifshitz过渡,两个狄拉克锥合并。在跃迁时,电子光谱的特征是在一个方向上有大量的二次色散,而在另一个方向上保持线性。我们发现,在最低阶,裸微扰理论中对准粒子质量的非常规对数平方(双对数)修正导致微扰重整化群方程的精确全解重化为强质量重整化.这种行为有效地消除了色散的曲率,并导致狄拉克锥恢复在低能量:系统流向狄拉克色散,这是各向异性的,但线性的动量,与相互作用依赖的对数调制。与恢复的临界狄拉克谱相关的贝里相位为零--这一性质由时间反演对称性保证,并且不受重整化的影响。我们的结果是在对比的行为,已发现在大-$N$的方法。

英文摘要:

We aim to understand how the spectrum of semi-Dirac fermions is renormalized due to long-range Coulomb electron-electron interactions at a topological Lifshitz transition, where two Dirac cones merge. At the transition, the electronic spectrum is characterized by massive quadratic dispersion in one direction, while it remains linear in the other. We have found that, to lowest order, the unconventional log squared (double logarithmic) correction to the quasiparticle mass in bare perturbation theory leads to resummation into strong mass renormalization in the exact full solution of the perturbative renormalization group equations. This behavior effectively wipes out the curvature of the dispersion and leads to Dirac cone restoration at low energy: the system flows towards Dirac dispersion which is anisotropic but linear in momentum, with interaction-depended logarithmic modulation. The Berry phase associated with the restored critical Dirac spectrum is zero - a property guaranteed by time-reversal symmetry and unchanged by renormalization. Our results are in contrast with the behavior that has been found within the large-$N$ approach.

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