Complex magnetic phases in polar tetragonal intermetallic NdCoGe$_3$

TL;DR

This study investigates the complex magnetic phases in the polar tetragonal intermetallic NdCoGe$_3$, revealing incommensurate magnetic structures and expanding the phase diagram with additional magnetic phases through neutron diffraction analysis.

Contribution

It provides new insights into the magnetic structures of NdCoGe$_3$, a noncentrosymmetric tetragonal material, and updates the magnetic phase diagram with previously unreported phases.

Findings

Incommensurate magnetic order below 3.70 K and 3.50 K.

Multiple magnetic phases exist for both zero and applied magnetic fields.

Magnetic structures are complex and involve modulated magnetic moments.

Abstract

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 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 and multi-$\vec{k}$ spin models are discussed. These results demonstrate that NdCoGe3 hosts complicated magnetic order derived from modulated magnetic moments.