INFLUENCE OF FILM MORPHOLOGY ON THIN-FILM FERROMAGNETISM

Cobalt, nickel and their alloy, Co1Ni9, films were epitaxially grown on Cu(100) under different growth conditions and subsequent treatments and studied using surface magneto-optic Kerr effect (SMOKE) in an attempt to understand the effects of film morphology on the magnetic properties. CO contamination can significantly reduce the magnetization and Curie temperature. Thermal desorption spectroscopy (TDS) shows that CO desorbs at 422 K from Ni and 410 K from Co1Ni9 at a heating rate of 6 K per minute. Annealing the films below 450 K produces smooth and clean films with stable magnetic behavior. However, annealing at higher temperatures results in Cu segregation and island formation leading to the finite-size ferromagnetic or even superparamagnetic behavior.