Anisotropic magnetic structures of the MnRMnSbO6 high pressure double double perovskites

Abstract

A new type of doubly ordered perovskite (also reported as double double perovskite, DDPv) structure combining columnar and rock-salt orders of the cations at the A and B sites, respectively, was recently found at high pressure for MnRMnSbO6 (R = La–Sm). Here we report further magnetic structures of these compounds. Mn2+ spins align into antiparallel ferromagnetic sublattices along the x axis for MnLaMnSbO6, while the magnetic anisotropy of Pr3+ magnetic moments induces their preferential order along the z direction for MnPrMnSbO6. The magnetic structure of MnNdMnSbO6 was reported to show a spin-reorientation transition of Mn2+ spins from the z axis towards the x axis driven by the ordering of Nd3+ magnetic moments. The crystal-field parameters for Pr3+ and Nd3+ at the 4e C2 site of their DDPv structure have been semiempirically estimated and used to derive their energy levels and associated wave functions. The results demonstrate that the spin-reorientation transition in MnNdMnSbO6 arises as a consequence of the crystal-field-induced magnetic anisotropy of Nd3+.