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arXiv 2108.06346cond-mat.str-elhep-lat
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Dirac系统中的金属临界性和非限制量子临界性

Metallic and Deconfined Quantum Criticality in Dirac Systems

Zi Hong Liu, Matthias Vojta, Fakher F. Assaad, Lukas Janssen

摘要:

受自旋轨道液体物理学的启发,我们研究了双层蜂窝晶格上相互作用的狄拉克费米子模型,该模型具有明显的SO(3)$\times$ U(1)对称性.利用大尺度相干场量子蒙特卡罗(QMC)模拟,我们发现了两个零温相变随相互作用强度的变化。首先,我们观察到从弱相互作用的半金属到不同的半金属相的连续过渡,其中SO(3)对称性自发破缺,三个狄拉克锥中有两个获得质量间隙。相关的量子临界点可以用Gross-Neveu-SO(3)理论来理解。其次,我们随后观察到一个过渡到绝缘相,其中SO(3)对称性恢复和U(1)对称性自发破缺。虽然在平均场水平下强烈的一阶,QMC数据是一致的直接和连续的过渡。因此,它是一个候选人的一种新型的取消限制的量子临界点,功能无隙费米自由度。

英文摘要:

Motivated by the physics of spin-orbital liquids, we study a model of interacting Dirac fermions on a bilayer honeycomb lattice at half filling, featuring an explicit global SO(3)$\times$U(1) symmetry. Using large-scale auxiliary-field quantum Monte Carlo (QMC) simulations, we locate two zero-temperature phase transitions as function of increasing interaction strength. First, we observe a continuous transition from the weakly-interacting semimetal to a different semimetallic phase in which the SO(3) symmetry is spontaneously broken and where two out of three Dirac cones acquire a mass gap. The associated quantum critical point can be understood in terms of a Gross-Neveu-SO(3) theory. Second, we subsequently observe a transition towards an insulating phase in which the SO(3) symmetry is restored and the U(1) symmetry is spontaneously broken. While strongly first order at the mean-field level, the QMC data is consistent with a direct and continuous transition. It is thus a candidate for a new type of deconfined quantum critical point that features gapless fermionic degrees of freedom.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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