COEXISTING FERROMAGNETISM AND HELIMAGNETISM IN DY Y SUPERLATTICES/

Neutron diffraction studies on Dy/N superlattices grown with the c axi s at an angle of approximately 35 degrees to the film plane reveal a c oexistence of helical antiferromagnetic order and ferromagnetic order. The coexistence of magnetic phases has been determined to arise from the development during growth of surface facets of the Y buffer layer, which was grown on bcc (211) Ta or Nb substrates. One of the superlat tice facets produces an isotropic expansion of the Dy basal plane whic h favors the helical antiferromagnetic spin configuration, while the o ther facet causes an anisotropic contraction of the Dy basal plane tha t favors ferromagnetism. The net result of the growth anomaly is the a pparent coexistence of the two magnetic states as observed by neutron scans made with the scattering vector oriented parallel to the nominal c crystal axis of the superlattice. (C) 1997 American Institute of Ph ysics.