The geometry of some crystal structures can cause geometric frustration, as neighbouring spins cannot form a configuration where their interactions are all favourable. This frustration can lead to exotic magnetic states, which can either be ordered or disordered. In some cases, both of these are present in one system. These partially ordered systems could be useful in magnetic materials, such as magnetic skyrmions, but the nature of the magnetic structure is difficult to determine.
In particular, it is challenging to distinguish between magnetic structures that combine multiple periodicities, known as 2-k, 3-k, and 4-k structures. In this study, published in npj Quantum Materials, researchers used neutron diffraction data measured at ISIS and ILL to investigate the partially ordered magnetic system Gd2Ti2O7. These results, combined with a comprehensive symmetry analysis and inelastic neutron scattering data collected at NIST and ORNL, enabled them to characterise the low temperature magnetic state of Gd2Ti2O7 as 2-k. Their work shows that it is possible to distinguish between single-k and multi-k structures without the need for single crystals or the application of external fields.
Related publication: Suppressed-moment 2-k order in the canonical frustrated antiferromagnet Gd2Ti2O7, npj Quantum Materials, 6, 99 (2021) DOI: 10.1038/s41535-021-00391-w