Perpendicular versus in-plane magnetization in a 2D Heisenberg monolayer at finite temperatures

Abstract

We show that the two-dimensional Heisenberg monolayer with perpendicular ground-state spontaneous magnetization may have a temperature ${\mathit{T}}_{\mathit{R}}$ at which the spontaneous magnetization turns into the plane of the monolayer. The reorientation of the magnetization occurs via a phase transition.