Identify the low-temperature magnetic phase of aluminium-substituted HoFeO3

Identify unambiguously whether the low-temperature phase observed in HoFe1−xAlxO3 for aluminium-substituted compositions is the mixed Γ12 phase or a pure Γ1 phase, using measurements capable of distinguishing the two magnetic structures.

Background

The paper investigates how replacing magnetic Fe3+ ions with nonmagnetic Al3+ ions changes the spontaneous spin-reorientation transition in HoFe1−xAlxO3. Magnetization measurements indicate that aluminium substitution broadens the temperature range assigned to the intermediate Γ12 phase and suppresses the Γ2 phase found in parent HoFeO3.

The authors note that the Γ1 and Γ12 phases cannot be distinguished unambiguously using their magnetization data alone. Consequently, the phase is labelled Γ12, while the possibility that it is a pure Γ1 phase remains unresolved. Resolving this ambiguity would require complementary measurements of the magnetic structure or another quantity sensitive to the orientation of the antiferromagnetic and ferromagnetic vectors.

References

However, based solely on our magnetization data, the Γ1 phase cannot be unambiguously identified from Γ12 and for that reason we label this phase as Γ12 keeping in mind that it also might be a pure Γ1.

— Effect of Magnetic Vacancies on the Spontaneous Spin-Reorientation Transition in HoFe$_{1-x}$Al$_x$O$_3$ Single Crystals  (2608.16348 - Skorobogatov et al., 17 Aug 2026) in Section Discussion, paragraph beginning “At lower temperatures”