Non-collinear magnetism in multiferroic perovskites

We present an overview of the current interest in non-collinear magnetism in multiferroic
perovskite crystals. We first describe the different microscopic mechanisms giving rise to
the non-collinearity of spins in this class of materials. We discuss, in particular, the interplay
between non-collinear magnetism and ferroelectric and antiferrodistortive distortions of the
perovskite structure, and how this can promote magnetoelectric responses. We then provide
a literature survey on non-collinear multiferroic perovskites. We discuss numerous examples
of spin cantings driving weak ferromagnetism in transition metal perovskites, and of spin-
induced ferroelectricity as observed in the rare-earth based perovskites. These examples are
chosen to best illustrate the fundamental role of non-collinear magnetism in the design of
multiferroicity.