MAGNETIC-PROPERTIES OF FE NI BILAYERS

A series of Fe/Ni bilayers with constant Ni layer thickness of d(Ni) = 140 Angstrom and various Fe layer thickness were grown in ultrahigh v acuum on Si(100) substrates. Magnetic properties were studied from 300 to 5 K by a SQUID magnetometer. The averaged magnetic moment of the F e layers was found to be strongly dependent on the thickness. For Fe l ayers of 32 Angstrom or less, a very low Fe moment was observed, which is about a factor of ten smaller than that of bulk bcc Fe, whereas fo r an Fe layer of 40 Angstrom the moment increases evidently. This resu lt might be attributed to a structural phase transition from fee to bc c structured Fe films. In the whole temperature range the magnetizatio n was found to be in the film plane. Furthermore, it was also observed that the coercivity of the bilayers depends on thickness and temperat ure.