Spontaneous Rotation of Ferrimagnetism Driven by Antiferromagnetic Spin Canting

Spin-reorientation phase transitions that involve the rotation of a crystal’s magnetization have been well characterized in distorted-perovskite oxides such as orthoferrites. In these systems spin reorientation occurs due to competing rare-earth and transition metal anisotropies coupled via $f\text{−}d$ exchange. Here, we demonstrate an alternative paradigm for spin reorientation in distorted perovskites. We show that the $R_2{\mathrm{CuMnMn}}_4{\mathrm{O}}_{12}$ ($R=\mathrm{Y}$ or Dy) triple $A$-site columnar-ordered quadruple perovskites have three ordered magnetic phases and up to two spin-reorientation phase transitions. Unlike the spin-reorientation phenomena in other distorted perovskites, these transitions are independent of rare-earth magnetism, but are instead driven by an instability towards antiferromagnetic spin canting likely originating in frustrated Heisenberg exchange interactions, and the competition between Dzyaloshinskii-Moriya and single-ion anisotropies.