Phase transformations in Mn/Fe(001) films: Structural and magnetic investigations

The solid-phase synthesis in epitaxial Mn/Fe(001) bilayer film systems with 24 at % of Mn has been shown to start at a temperature of 220°C with the formation of a γ-austenite lattice and the Mn and Fe films react completely under annealing to 600°C. In the sample cooling process after annealing below 220°C, the γ austenite undergoes a martensitic transformation to an oriented ∈(100) martensite. When the annealing temperature is increased above 600°C, Mn atoms migrate from the γ-lattice, which becomes unstable, and the film is partially again transformed to the epitaxial Fe(001) layer. The solid-phase synthesis in Mn/Fe(001) bilayer nanofilms and multilayers is assumingly determined by the inverse ε → γ martensitic transformation in the Mn-Fe system. The existence of a new low-temperature (~220°C) structure transition in the Mn-Fe system with a high iron content is assumed.