Magnetic Phase Transition of [Fe/Au] Multilayers with an Ultra-thin Fe Layer

Abstract

The magnetic phase transition of [m ML Fe/12.5 ML Au] 20 (m=0.7, 0.9, 1.1) multilayers was investigated. The quality of samples was well defined by RHEED observation and the 4 circle X-ray diffraction method. Perpendicular anisotropy was observed for samples thinner than 2ML Fe. The Curie temperature TC and a critical exponent β were precisely determined by the new method to evaluate the spontaneous magnetization from the measured magnetization as a function of temperature. The Curie temperature TC decreased with decreasing Fe thickness. The critical exponent β for an ultra-thin Fe layer of around 1 ML is similar to that for the Heisenberg model. The spacer layer of Au plays an important role in making the system's three-dimensional ferromagnetism.