论文标题
在魔法角度附近的扭曲双层石墨烯中的集体激发和等离子体光谱
Collective excitations and plasmon spectrum in twisted bilayer graphene near the magic angle
论文作者
论文摘要
由于观察到非常规超导和相关的绝缘行为，因此具有微小旋转角的扭曲双层石墨烯引起了极大的关注。在本文中，我们采用完整的紧密结合模型来调查旋转双层石墨烯近乎魔术角的集体激发。极化函数是从没有哈密顿基质对角线的紧密结合传播方法获得的。在模拟中考虑的原子弛豫时，在室温和超导性过渡温度下，在魔法角度上发现了阻尼和未固定的边缘等离子体模式。特别是，可以在超导性过渡温度下以魔法角扭曲的双层石墨烯直接探测狭窄带中的未阻尼等离子体模式。未阻尼的等离子模式可调节，角度逐渐随温度和化学势而逐渐消失。实际上，可以通过探索测得的能量损耗函数的集体等离子来检测扭曲的双层石墨烯中的平坦带。
Twisted bilayer graphene with tiny rotation angles have drawn significant attention due to the observation of the unconventional superconducting and correlated insulating behaviors. In this paper, we employ a full tight-binding model to investigate collective excitations in twisted bilayer graphene near magic angle. The polarization function is obtained from the tight-binding propagation method without diagonalization of the Hamiltonian matrix. With the atomic relaxation considered in the simulation, damped and undamped interband plasmon modes are discovered near magic angle under both room temperature and superconductivity transition temperature. In particular, an undamped plasmon mode in narrow bands can be directly probed in magic angle twisted bilayer graphene at superconductivity transition temperature. The undamped plasmon mode is tunable with angles and gradually fades away with both temperature and chemical potential. In practice, the flat bands in twisted bilayer graphene can be detected by exploring the collective plasmons from the measured energy loss function.
