Two-dimensional magnet at Curie temperature: Epitaxial layers of Co on Cu(100)

The response of magnetization to the application of a magnetic field has been measured above the Curie temperature ${\mathit{T}}_{\mathit{C}}$ in epitaxial Co films on Cu(100). Magnetic domain images have been acquired up to ${\mathit{T}}_{\mathit{C}}$. The results suggest that for temperatures T>${\mathit{T}}_{\mathit{C}}$ the system behaves like a two-dimensional Heisenberg magnet.