Nature and origin of consecutive magnetic transitions in fcc antiferromagnets

Determine the nature of the second ordered state and the origin of two consecutive magnetic transitions in fcc antiferromagnets, including the roles of symmetry lowering and competing exchange and dipolar couplings in Ba₂GdSbO₆.

Background

The paper reports two consecutive magnetic transitions in Ba₂GdSbO₆, whereas most fcc antiferromagnets exhibit only one magnetic transition. It notes that successive transitions can arise from symmetry lowering, with partial magnetic order appearing at the higher-temperature transition and complete order developing at the lower-temperature transition. However, consecutive transitions can also occur in undistorted fcc antiferromagnets, so the structural origin is not established.

The authors further point out that the material combines geometrical frustration with competing antiferromagnetic exchange and dipolar interactions. Resolving the microscopic nature of the low-temperature ordered phases and identifying the mechanism producing the two transitions would clarify the magnetic behavior of Ba₂GdSbO₆ and the broader role of exchange–dipolar competition in fcc magnets.

References

Two consecutive transitions may also occur in an undistorted fcc antiferromagnet exemplified by Ba$_2$YOsO$_6$, but the nature of the second ordered state and the origin of the two transitions have not been resolved in the literature.

— Frustrated Gd3+ Double Perovskites as High-Performance Magnetocaloric Materials for Sub-100 mK Adiabatic Demagnetization Refrigeration  (2609.36538 - Treu et al., 29 Sep 2026) in Section 2, Results and Discussion, subsection “Quasi-Adiabatic Demagnetization Refrigeration”