Spin excitations of a distorted antiferromagnetic Kagome material CrNiAs

Kagome metals, with a frustrated sub-lattice, are ideal hosts for many exquisite quantum phenomena. Take the CrFeAs, for example, which shows a non-metallic behavior with in-plane negative dρ/dT from ∼ 800 K to below 100 mK, but the absolute resistivity is very low. The inelastic neutron scattering measurements of polycrystalline samples reveal high-velocity gapless spin wave excitations persisting to 80 meV, which resemble spin excitations in itinerant magnets like chromium. We recently synthesized a distorted Kagome single crystal CrNiAs with an anomalous Hall effect and “non-metallic” behavior similar to the case in CrFeAs.Our recent neutron diffraction experiments conducted at SXD have demonstrated that the sample exhibits antiferromagnetism with the magnetic propagation vector equal to (1/3, 1/3, 1/2) below TN = 80K with about 0.8μB in Cr3+ and 0.2μB in Ni3+, ferromagnetism between TC ~ 130K and TN. To explain the origin of the unusual temperature dependence of resistivity and weak AHE, it would be interesting to search for novel spin excitations in CrNiAs under the competing magnetic interactions from Cr and Ni. We have already grown high-quality CrNiAs single crystals of about 3g. Here we propose to do time-of-flight experiments on MAPS. The measurements will take about 8 days.