Polar materials can host a variety of topologically significant magnetic phases, which often emerge from a modulated magnetic ground state. Relatively few noncentrosymmetric tetragonal materials have been shown to host topological spin textures and new candidate materials are necessary to expand the current theoretical models. This manuscript reports on the anisotropic magnetism in the polar, tetragonal material ${\mathrm{NdCoGe}}_3$ via thermodynamic and neutron diffraction measurements. The previously reported $H-T$ phase diagram is updated to include several additional phases, which exist for both $H$ = 0 and with an applied field $H\perp c$. Neutron diffraction data reveal that the magnetic structures below $T_{N1}$ = 3.70 K and $T_{N2}$ = 3.50 K are incommensurate, with a ground-state magnetic order that is incommensurate in all directions with the propagation vector $\vec{k}$ = (0.494, 0.0044, 0.385) at 1.8 K. A unique magnetic structure solution is not achievable, but the possible single-$\vec{k}$ and multi-$\vec{k}$ spin models are discussed. These results demonstrate that ${\mathrm{NdCoGe}}_3$ hosts complicated magnetic order derived from modulated magnetic moments.

• Received 29 October 2020
• Revised 18 December 2020
• Accepted 23 December 2020

DOI:https://doi.org/10.1103/PhysRevB.103.014426