Magnetic and structural instabilities of ferromagnetic and antiferromagnetic Fe/Cu(100)

Fe wedges epitaxially grown on Cu(100) have been employed to investigate the interplay between magnetic and structural instabilities. 2–4 monolayer (ML) clean Fe films grown at room temperature are ferromagnetic with perpendicular easy axes. bcc Fe films≳11 ML thick are ferromagnetic with in-plane easy axes. Most importantly, 6–11 ML fcc Fe films are antiferromagnetic and have a ferromagnetic surface. Films grown below 200 K and annealed to room temperature do not exhibit the antiferromagnetic phase, but remain ferromagnetic and undergo a spin-reorientation transition from perpendicular to in plane at ∼6 ML. A new phase diagram for Fe/Cu(100) is proposed as a function of thickness and growth temperature. In addition, an impurity-stabilized layer-by-layer growth that persists to 30–40 ML Fe is also reported.