The thickness dependence of both the perpendicular and in-plane magnet
ization is observed for pseudomorphic ultrathin, fcc Fe epitaxial film
s grown on room temperature Cu(100). Ferromagnetically ordered 3.5-mon
olayer-thick films display both in-plane and perpendicular remanence.
Perpendicular remanence, lost after a 9.0 kOe static field is applied
perpendicular to the film plane, can be restored by either heating or
applying large in-plane fields. These field-induced metastable states
are interpreted in terms of magnetoelastic effects which modify the ex
change and anisotropy constants both perpendicular to and within the f
ilm plane.