Heusler compounds are a class of materials having the representative formula X2YZ, where X and Y are transition metals or lanthanides, and Z is from a main group element. Due to the chemical distinction between X or Y and Z, they form a unique structure defined by the space group symmetry L21 (or D022 when they are tetragonally distorted), where four face-centered cubic structures penetrate each other. The properties of Heusler compounds are strongly dependent on the chemical ordering of the elements constituting the compounds. Thus, the fabrication of high quality Heusler films typically requires high temperature thermal processes: for example, deposition at temperatures significantly above room temperature and/or thermal annealing at high temperatures (400° C. or higher).
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