First‐order line and critical end point of cubic rare‐earth pseudobinaries in RxR’1−xT2 in the H, X plane (abstract)

We study the effects that an applied magnetic field has on the nature of the off‐principal axis magnetic phases of rare‐earth‐transition metal pseudobinaries. The magnetic field is taken to be in the (011) plane of these cubic materials but is otherwise arbitrary. Besides the expected second‐order transition which takes place only when the field is in the [100] direction, there occurs a low‐field first‐order transition which separates two spin‐canted phases. This transition is predicted for a range of concentration between the zero‐field spin‐canted/[111] boundary x0 and a somewhat larger concentration of [111]‐easy rare earths x1. The field at the first‐order transition is a monotonically increasing function of concentration within this range, starting at zero at x0 and reaching a critical field Hc of the order of D2/JMs at x1, where D is the fourth‐order crystal‐field strength and  J is the exchange energy density. The point Hc, x1 is a critical end point in the H, x plane. The random fluctuations in s...