A well-known property of Fe/Cu(100) films is the existence of “magnetic live surface layers above ∼4ML (monolayer). This is correlated with structural changes as seen with low electron energy diffraction. Up to ∼4ML a(n×1) diffraction pattern is observed with n∼5. This changes into a pattern with a (2×1) symmetry for thicker films. We have studied the evolution of the structural and magnetic properties of FexNi1-x and FexMn1-x/Cu(100) films with Fe contents above 80%. The magnetic studies indicate two types of magnetic behavior. Initially the films are uniformly magnetized as judged from the thickness dependence of the Kerr signal. In this thickness regime the (n×1) diffraction pattern shows a thickness dependence of n. For all samples we find that n varies linearly from 4-6 in the thickness regime 2-4 ML. The uniformly magnetized state is followed by a phase with constant Kerr intensity. This change in the magnetic properties is accompanied by a change in the diffraction pattern which becomes either (2×1) or p(1×1). Further, we find the easy axis is normal to the surface for the uniformly magnetized films and magnetic live surface layers. We discuss our results in the context of a nanomartensitic bcc phase recently observed for Fe/Cu(100). © 2004 The American Physical Society.