Investigation of the magnetic ground state of non-collinear antiferromagnet Mn3NiN

Spintronic devices utilising ferromagnets for memory applications are nearing their performance limits. An innovative approach to overcome these constraints involves using non-collinear antiferromagnets (NCAFMs). NCAFMs have garnered considerable interest due to their unique advantages, including ultrafast spin dynamics and higher packing densities resulting from minimal stray magnetic fields, making them superior to ferromagnets. During this beamtime, we focus on investigating Mn₃NiN, a key material within the NCAFM family. The small net moment in this material will allow the stabilisation of the single domain state, leading to a finite anomalous Hall resistivity, which can be detected electrically. While theoretical predictions suggest that the antiferromagnetic ground state of Mn₃NiN is driven primarily by the Mn atoms' contributions to the total magnetic moment, our previous measurements using X-ray magnetic circular dichroism (XMCD) have revealed a more complex magnetic structure. Specifically, we have observed finite magnetic moments not only from Mn atoms but also from Ni atoms, which challenges the conventional understanding of the material's magnetic ordering. To further investigate this, we plan to conduct experiments on Mn₃NiN samples with varying Ni concentrations, systematically analysing how Ni influences the overall magnetic moment of the system. By carefully evaluating the role of Ni, we aim to refine our understanding of the magnetic interactions within Mn₃NiN and potentially uncover new insights into the magnetic behaviour of NCAFMs.