Direction-dependent anisotropic exchange is a common feature of magnetic systems with strong spin-orbit coupling. Here we study the effect of such exchange upon macroscopic magnetic anisotropy for a face-centered-cubic model. By several theoretical techniques, we show that, both in the paramagnetic and ordered phases, the magnetic anisotropy is induced by fluctuations. Moreover, the magnetic anisotropy differs in the paramagnetic and ordered phases: in the paramagnetic phase the susceptibility is maximum along the $\langle 111\rangle$ directions, while the magnetic moments orient along $\langle 110\rangle$ or $\langle 100\rangle$ in the ordered phase. We suggest that such “anisotropy switching” can be a common feature of strongly spin-orbit-coupled magnets.

• Received 28 April 2015

DOI:https://doi.org/10.1103/PhysRevB.92.020411