Molecular Beam Epitaxy of Co 2 MnSi Films on Group-IV Semiconductors

We explore epitaxial growth of Co 2 MnSi films on Si(111) or Ge(111) by means of low-temperature molecular beam epitaxy. We find that as-grown Co 2 MnSi films consist of mixed phases with L2 1 -ordered structures and microcrystalline ones. As a result, the magnetic moment, which is nearly half of the ideal value, can be obtained even at very low growth temperature. Post-growth annealing was effective to crystallize the microcrystalline phases observed in the as-grown layer, leading to a further enhancement in the magnetic moment. We discuss a difference in growth mechanism between Co 2 MnSi and other Heusler alloys examined in our previous works.