Low energy electron diffraction and magneto-optical Kerr effect measurements were carried out in interleaved mode for epitaxially grown Fe/Cu(100) at temperature variation. What was believed to be a regular thermodynamic Curie transition in 4 monolayer Fe/Cu(100) is shown to be the result of a temperature-driven structural transformation.

• Received 5 February 1996

DOI:https://doi.org/10.1103/PhysRevLett.76.4620