Ferromagnetism in Magic-angle Twisted Bilayer Graphene: A Monte Carlo Study
Abstract
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.
Keywords
Cite
@article{arxiv.2206.14432,
title = {Ferromagnetism in Magic-angle Twisted Bilayer Graphene: A Monte Carlo Study},
author = {H. X. Zhang and Y. X. Gao and Z. J. Ding},
journal= {arXiv preprint arXiv:2206.14432},
year = {2022}
}
Comments
9 pages, 5 figures