ISIS Neutron and Muon Source Data Journal

Neutron diffraction study on Mn0.25Cr0.75Sb: resolving the magnetic structure at the collinear-to non-collinear altermagnetic crossover

Abstract: Altermagnetism (AM) is a newly identified magnetic phase in which opposite-spin sublattices are related by rotational symmetry, producing momentum-space spin-splitting and an anomalous Hall effect (AHE) without macroscopic magnetization. All confirmed altermagnets to date, including CrSb, possess collinear antiferromagnetic (AFM) order. Whether AM symmetry breaking survives in a non-collinear phase remains entirely untested, yet resolving this would fundamentally redefine the symmetry criteria for the entire class of altermagnetic materials. The MnxCr1-xSb series provides a unique platform to address this. Our WISH neutron data (October 2025) show that x = 0.1 remains collinear AFM with an AHE unexplained by the weak spontaneous magnetization, while x = 0.35 shows moment rotation into the ab plane, establishing a non-collinear AFM ground state. The x = 0.25 composition sits at the boundary of this transition, displaying a metamagnetic transition for BIIc and a zero-field Hall signal exceeding what the spontaneous magnetization can account for. Its magnetic structure and the fate of AM symmetry at the crossover remain unknown. We propose single-crystal neutron diffraction on WISH to determine the zero-field and field-dependent magnetic structure of Mn0.25Cr0.75Sb at 5 K. Refined magnetic space groups will be combined with DFT calculations to establish whether AM symmetry breaking persists in the non-collinear regime, the first experimental test of AM beyond collinear order.

Principal Investigator: Professor Leslie Schoop
Local Contact: Dr Fabio Orlandi
Experimenter: Dr Sudipta Chatterjee

DOI: 10.5286/ISIS.E.RB2620153

ISIS Experiment Number: RB2620153

Publisher: STFC ISIS Neutron and Muon Source

Data format: RAW/Nexus
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Data Citation

The recommended format for citing this dataset in a research publication is as:
[author], [date], [title], [publisher], [doi]

For Example:
Professor Leslie Schoop et al; (2026): Neutron diffraction study on Mn0.25Cr0.75Sb: resolving the magnetic structure at the collinear-to non-collinear altermagnetic crossover, STFC ISIS Neutron and Muon Source, https://doi.org/10.5286/ISIS.E.RB2620153

Data is released under the CC-BY-4.0 license.