Study Of Magnetic Properties In Dy/Y Superlattices By Neutron Scattering^*. H. Kaiser, K.A. Hamacher, J.J. Rhyne (University of Missouri Research Reactor, Columbia);K.A. Ritley, C.P. Flynn (University of Illinois, Urbana); K. Theis-Bröhl (Ruhr-Universität, Bochum, Germany).

The magnetic properties of bulk Dy are very different from those in Dy/Y superlattices¹, where Dy is sandwiched between a nonmagnetic material such as yttrium. We have studied extensively, through neutron diffraction, the magnetic behavior of a new Dy/Y superlattice system, for which the growth axis (surface normal) is not along one of the principal axis directions but rather at an angle of about 35deg. to the c-axis. A new and striking result was found^2-3, that is, the coexistence of helical antiferromagnetic order and ferromagnetic order. This is the first time that ferromagnetism has been observed in Dy/Y superlattices. This result is very different from c-axis growth Dy/Y superlattices¹, which exhibit only helimagnetism because of the effect of epitaxial clamping on the magnetorestrictive strain energy. RHEED and x-ray measurements showed that these new Dy/Y superlattices consist of facets, actually of two different superlattice types on a mesoscopic scale. These facets nucleate in the Y buffer layer and become more developed with growth of the Dy/Y bilayers. Our study shows that the faceted superlattice structure is the source of the two coexistent magnetic phases.

[1] J.J. Rhyne, M.B. Salamon, C.P. Flynn, R.W. Erwin, and J.A. Borchers, J. Magn. Magn. Mat. 129, 39 (1994).

[2] K. Theis-Bröhl, K.A. Ritley, C.P. Flynn, K. Hamacher, H. Kaiser, .J. Rhyne, J. Appl. Phys. 79, 4779 (1996).

[3] K. Theis-Bröhl, K.A. Ritley, C.P. Flynn, J.E. Van Nostrand, K. Hamacher, H. Kaiser, J.J. Rhyne, J. Magn. Magn. Mat. 166, 27 (1997).

^*This work is supported by ONR Grant N00014-94-1-1146, DFG Grant Br 1466/2-1, NATO Grant CRG.960979, and NSF GRANT DMR91-21888.