论文标题
魔术角扭曲双层石墨烯中的铁磁性：一项蒙特卡洛研究
Ferromagnetism in Magic-angle Twisted Bilayer Graphene: A Monte Carlo Study
论文作者
论文摘要
当通过在魔术扭转角度堆叠两个石墨烯单层形成的Moire超级晶格时，就会出现铁磁性。这项工作根据四分之一填充的三角形晶格的伊辛模型研究了铁磁性，在半填充时是一个方形格子，在四分之三的电子中填充了kagome晶格。使用蒙特卡洛方法在零磁场上计算温度依赖的热容量，磁化率，能量和磁化曲线，从而得出了相变温度，T_C = 0.76、1.33和4.75 K。在有限磁场处的磁化曲线显示出所有所考虑的填充物在0.5 k以下的温度下显示出强滞后，表明系统的铁磁剂。结果与实验观察一致。
Ferromagnetism emerges when the Moire superlattice formed by stacking two graphene monolayers in a magic twist angle are filled with integer number electrons. This work investigates the ferromagnetism based on the Ising models for a triangular lattice at one-quarter filling, a square lattice at half filling and a Kagome lattice at three-quarters filling of electrons. The temperature dependent heat capacity, magnetic susceptibility, energy and magnetization curves are calculated at zero magnetic field with a Monte Carlo method, leading to derive the phase transition temperatures, T_c=0.76, 1.33 and 4.75 K, respectively. Magnetization curves at finite magnetic field show strong hysteresis at temperature below 0.5 K for all the fillings considered, indicating the ferromagnetism of the system; the results are in agreement with experimental observations.
