The ``Acknowledgements'' section, and sections 1, 2,
3, 4, 5, and 6, of
this document, form a transcript of a talk, given in the ``Novel
Techniques in Magnetism'' meeting of the CMD19CMMP
2002
conference, organized
by the European Physical
Society
and the Institute
of Physics. The ``Abstract'' is that which
appeared in the abstracts book for this conference, and on the basis
of which the talk was accepted for inclusion in the conference.