title: Edge magnetism of Heisenberg model on honeycomb lattice.
abstract: Edge magnetism in graphene sparks intense theoretical and experimental interests. In the previous study, we demonstrated the existence of collective excitations at the zigzag edge of the honeycomb lattice with long-ranged Néel order. By employing the Schwinger-boson approach, we show that the edge magnons remain robust even when the long-ranged order is destroyed by spin fluctuations. Furthermore, in the effective field-theory limit, the dynamics of the edge magnon is captured by the one-dimensional relativistic Klein-Gordon equation. It is intriguing that the boundary field theory for the edge magnon is tied up with its bulk counterpart. By performing density-matrix renormalization group calculations, we show that the robustness may be attributed to the closeness between the ground state and the Néel state. The existence of edge magnon is not limited to the honeycomb structure, as demonstrated in the rotated-square lattice with zigzag edges as well. The universal behavior indicates that the edge magnons may attribute to the uncompensated edges and can be detected in many two-dimensional materials.
authors.affiliation: Department of physics, National Chung Hsing University, Taichung 40227, Taiwan.
authors.forename: Wen-Min
authors.initials: WM
authors.lastname: Huang
authors.affiliation: Faculty of Science and Technology, Gunma University, Kiryu, Gunma 376-8515, Japan.
authors.forename: Toshiya
authors.initials: T
authors.lastname: Hikihara
authors.affiliation: Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Yen-Chen
authors.initials: YC
authors.lastname: Lee
authors.affiliation: Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan.
authors.forename: Hsiu-Hau
authors.initials: HH
authors.lastname: Lin
mesh_terms: D000465:Algorithms; D008962:Models, Theoretical