The magnetic susceptibility of a triangular-graphene-quantum-dot-like system
was examined by using the determinant quantum Monte Carlo method. We focused on
three kinds of zigzag edge quantum dots or rings, namely the triangular
graphene quantum ring, twist bilayer triangular graphene quantum dot, and twist
bilayer triangular graphene quantum ring. The
triangular-graphene-quantum-dot-like system exhibits robust edge ferromagnetic
behavior, which is independent of size, monolayer or bilayer, and dot or ring
shape, according to the unbiased numerical results. At half filling, the edge
magnetic susceptibility is increased by on-site interaction, especially in low
temperature region. Applications of this system in spintronics may benefit from
the robust edge ferromagnetic behavior.Comment: 6 pages, 7 figure