Is gadolinium a helical antiferromagnet or a collinear ferromagnet?

Abstract

Controversial issues concerning the nature of magnetic ordering in gadolinium are briefly reviewed. The recent experimental results are shown to resolve most of such issues in that they rule out the possibility of a helical spin structure in Gd and clearly bring out the role of longrange dipolar interactions in stabilising collinear ferromagnetic order for temperatures between the spin-reorientation temperature and the Curie point.