Engineering coercivity in epitaxially grown (110) films of DyFe2-YFe2 superlattices

Molecular beam epitaxial methods have been used to grow single crystal Laves phase DyFe2-YFe2 superlattice samples with a (110) growth direction. It is shown that it is possible, in principle, to engineer a desired coercivity between the limits K(DyFe2)less than or equal to K less than or equal to infinity. This can be achieved by adjusting the relative thickness of the individual DyFe2 and YFe2 layers, in multilayer films This novel feature is illustrated, using the superlattice films [x Angstrom DyFe2/(100-x) Angstrom YFe2]x40, with x=80, 60, 50, and 45. It is found that the measured coercivity is in semiquantitative agreement with a simple theoretical expression, for the nucleation fields in both bilayer and multilayer compounds. However, in practice, exchange spring penetration into the DyFe2 layers can set a limit to the maximum coercivity that can be achieved. (C) 2000 American Institute of Physics. [S0003-6951(00)03730-X].