Search for the magnetic structure of a distorted Kagome CrNiAs

Kagome metals, with a frustrated sub-lattice, are ideal hosts for many exquisite quantum phenomena. Taking the kagome-metal Co3Sn2S2 for example, the nodal ring transforms into Weyl nodes under strong spin-orbit coupling (SOC), with intrinsic Berry curvature and ferromagnetic order contributing to a giant anomalous Hall effect. We recently synthesized a distorted Kagome single crystal CrNiAs with an anomalous Hall effect, similar to the Co3Sn2S2 compound. The ternary arsenide CrNiAs is a ferromagnet with the Curie temperature, Tc, reported to be 171.9 K, and the magnetic moment per formula unit reported to be 2.42 μB in powder. The hyperfine magnetic moment field at 61Ni nuclei implies that the Ni atoms carry a magnetic moment of 0.15(3) μB, and the moment carried by the Cr atoms is 0.95(6) μB. From powder neutron diffraction experiments, the compound is ferromagnetic mainly from the Cr moment of 1.25(5) μB in the 110-182 K. Below 110 K, it reveals typical satellite reflections whose propagation vector is 0.228 c*. The behavior of the anomalous Hall effect with temperature is the same as that of the moment. So measuring the magnetic structure of CrNiAs is crucial to explain its anomalous Hall effect. We have already prepared large crystals sized up to 3 mm. We propose to do neutron Laue diffraction at 4 K 100 K, and 200 K (reference point) using the top-loading CCR at the single crystal diffractometer SXD. The measurements will take about 5 days.