Magnetic phase transition of ultrathin Fe layers in Fe/Au multilayers

The magnetic phase transition of Fe layers is investigated in Fe(2 Angstrom)/Au(d) multilayers with d = 5 to 200 Angstrom by means of magnetization measurements. For d < 10 Angstrom, the Curie temperature T-C is above 300 K. With increasing d, an overall decrease of T-C is observed. Reference samples including a single Fe(2 Angstrom) layer show T-C approximate to 80 K, which is lower than T-C approximate to 150 K for 200 Angstrom greater than or equal to d > 100 Angstrom. The interlayer coupling between Fe layers mediated by Au layers remains even for long distances exceeding 100 Angstrom. It is expected that even a weak interlayer coupling suppresses the spin fluctuation in two-dimensional magnets and shifts T-C to a higher temperature.