Microscopic origin of the 60–88 K diffraction anomaly

Determine the microscopic origin of the abnormal temperature dependence of selected neutron-diffraction reflections in bulk b1-MnTe between approximately 60 and 88 K, including whether it arises from intrinsic piezomagnetic or magnetoelastic effects.

Background

The study observes a history-dependent decrease in the intensity of selected reflections from approximately 60.5 to 88.5 K under field-cooled cooling, together with an abrupt change in the measured d-spacing near 61 K. The anomaly is not accompanied by a resolvable out-of-plane spin rotation or explained by the minor MnTe2 impurity phase.

The authors discuss several possible intrinsic mechanisms, including piezomagnetically driven magnetic-domain repopulation, magnetoelastic coupling, enhanced primary extinction, and detwinning of time-reversal domains caused by a small out-of-plane component of the applied field. The available unpolarized diffraction data do not establish which mechanism is responsible.

References

Furthermore, an abnormal behaviour in the temperature dependence of the selected reflections is observed in 60--88~K, while an extrinsic cause due to the minority impurity phase can be ruled out, its microscopic origin, discussed within the context of possible intrinsic piezomagnetic or magnetoelastic effects, remains open.

— Magnetic-field-induced detwinning of orientational domains in altermagnet $α$-MnTe: A single-crystal neutron diffraction study  (2610.13444 - Pan et al., 9 Oct 2026) in Section 1, Introduction; Section 3.3, “Temperature dependence of the selected reflections”