Coexistence of different magnetic phases in Dy/Y superlattices caused by growth induced nanostructures

Epitaxial Dy/Y rare earth superlattices were prepared by molecular beam epitaxy on Ta(211) and Nb(211) buffer layers on alpha-Al2O3(<1(1)over bar 00>) and characterized via in situ reflection high-energy electron diffraction (RHEED), in situ scanning tunneling microscopy (STM) and ex situ X-ray and neutron diffraction. The Y buffer and the Dy/Y superlattice are found to grow strongly faceted on the Ta or Nb(211) buffer, and form 'growth induced' nanostructures with two different superlattice types on both facet surfaces. Magnetic measurements show two coexisting magnetic phases that are obtained in the temperature range below the Neel temperature. We develop a model to interpret this behavior in connection with the results of structural and magnetic measurements.