Magnetic properties of epitaxially grown Fe3 Si/Ge (111) layers with atomically flat heterointerfaces

We study magnetic properties of epitaxial Fe3 Si layers grown on Ge(111) with atomically flat interfaces. An unexpected uniaxial magnetic anisotropy is observed in the film plane for all as-grown samples, and the direction of the uniaxial easy axis is different for each of these samples. By postgrowth annealing, surprisingly, the random orientation of the uniaxial easy axis is aligned to a direction along about [0 1- 1], together with a reduction in the saturation magnetization. We discuss a possible mechanism of the variation in the magnetic properties after the annealing.