Identifying magnetic phases in chemically ordered and disordered FeAl thin films†

Direct magnetic writing of ferromagnetic nanoscale elements provides an alternative pathway for potential application in data storage or spintronic devices. Magnetic patterning due to local chemical disordering of Fe₆₀Al₄₀ thin films results in adjacent nanoscale regions that possess two different phases, viz. a low-magnetization and high-coercive chemically ordered phase (non-irradiated ferromagnetic area, NIFM) and a high-magnetization and low-coercive chemically disordered phase (irradiated ferromagnetic area, IMF). Depending on the volume of NIFM and IFM phases, different interaction mechanisms were revealed. It was shown that the modulated films of the coexisting magnetic phases do not lead to exchange coupling in most cases. Evidence for exchange-spring behaviour, however, was found. Moreover, both magneto-structural phases at low temperatures show spin-glass-like properties. Understanding the influence of chemical ordering on magnetic properties is crucial for the advancement of the functionalities of spintronic devices and for the development of alloys with controllable magnetic properties.