We use spherical neutron polarimetry to determine the ground state magnetic structure of Mn3Sn. We find that Mn3Sn adopts an inverse triangular structure with spins parallel to <100> (Type III) rather than spins parallel to <110> (Type IV). Density functional theory calculations reveal no energy difference between these two structures, suggesting that the selection is caused by subtle effects such as sixth-order anisotropy. Partial control of the magnetic domain population through a moderate magnetic field is key to distinguish between the two models. We find that three of the six domains are approximately equally populated, while the others have negligible population. Upon entering the low temperature incommensurate phase, the domain structure is lost. The domains decouple from the magnetic field, and can therefore not be controlled by any known method.
@article{arxiv.2510.06808,
title = {Ground state magnetic structure of Mn3Sn},
author = {Jeppe Jon Cederholm and Zhian Xu and Yanfeng Guo and Martin Ovesen and Thomas Olsen and Kristine M. L. Krighaar and Chrystalla Knekna and Jian Rui Soh and Youngro Lee and Navid Qureshi and Jose Alberto Rodriguez Velamazan and Eric Ressouche and Andrew T. Boothroyd and Henrik Jacobsen},
journal= {arXiv preprint arXiv:2510.06808},
year = {2026}
}