论文标题
扭曲的双重双层石墨烯的激子金属和非纤维液体行为靠近电荷中立
Excitonic Metal and Non-Fermi Liquid Behaviour in Twisted Double Bilayer Graphene near Charge Neutrality
论文作者
论文摘要
扭曲的双重双层石墨烯是电荷中性点附近的补偿半金属，其带状板中存在小电子和孔口袋。我们表明，电子和孔之间的强库仑吸引力可以导致间接激子的形成。这些激子在低温下的凝结会产生具有电荷密度波顺序的激子金属，从而达到适当的相互作用强度范围。这对系统中的低温运输具有有趣的含义，这是载体密度和温度的函数。单个颗粒激发及其在激子金属中状态的密度的重组会导致电阻率的峰值作为载体密度的函数，最近在低温下实验中可见。 Landau在量子临界金属中抑制订单参数的波动导致了非Fermi液体行为，这可以解释sublinear $ t^{2/3} $依赖电荷中性点附近的电阻。
Twisted double bilayer graphene is a compensated semi-metal near the charge neutrality point with the presence of small electron and hole pockets in its band structure. We show that strong Coulomb attraction between the electrons and holes can lead to the formation of indirect excitons. Condensation of these excitons at low temperature creates an excitonic metal with charge density wave order for an appropriate range of interaction strength. This has interesting implications for low-temperature transport in the system as a function of carrier density and temperature. The reorganization of the single particle excitations and their density of states in the excitonic metal can lead to peaks in resistivity as a function of carrier density, recently seen in experiments at low temperatures. The fluctuations of the Landau damped order parameter in the quantum critical metal lead to non-Fermi liquid behaviour, which can explain the sublinear $T^{2/3}$ dependence of the resistance near the charge neutrality point.
