MAGNETIC PHASE-TRANSITIONS OF ULTRA-THIN FE FILMS

Magnetic properties of ultra-thin Fe(100) films are studied experiment ally, with an emphasis on the temperature dependence of the magnetizat ion and the influence of the substrate on magnetic properties. It is f ound that the nature and orientation of the substrate, here Au(100) an d Pd(100), have significant effects on the character of the ferromagne tic phase transition, in particular the thermodynamic behavior near th e Curie point is strongly dependent on the detail of the system, in co ntrast to the case of bulk Fe. These results are consistent with predi ctions for the XY model with crystalline anisotropies.