Possible topological Hall effect in a binary Nd intermetallic compound

Skyrmions, which are particle-like spin textures with topological origin, are predicted in real space, and have been discovered in several compounds including MnSi, GdRu₂Si_2, and EuAl₄. So far, the magnetism in the materials hosting skyrmions has been attributed to either 3d transition metal ions or 4f⁷ rare earth ions with L = 0 (Gd³⁺ or Eu²⁺) [1]. Therefore, it is interesting to search for skyrmion material candidates beyond these magnetic ions, for instance, rare earth ions with L ≠ 0.

 

Here we identified an Nd intermetallic compound as such a candidate, where Nd³⁺ has L = 6. This system orders antiferromagnetically at T_N ~ 13.2 K, with multiple transitions below T_N. These transitions are also observed in zero-field neutron scattering measurements. Our compound is a superstructure of BaAl₄, with the former being structurally related to skyrmion material candidates [2,3].  We used magneto-transport data to map out a high-resolution field - temperature phase diagram. In addition, our preliminary magneto-transport measurements show a significant anomaly in the Hall effect in some of the magnetic phases, reaching values as high as 10⁵ Ohm^-1 cm^-1. This value far exceeds that expected from reciprocal space topology (10² – 10³ Ohm^-1 cm^-1), suggesting a possible origin from real space topology.

 

[1] Tokura, Y. and Kanazawa, N. Chem. Rev. 121, 2857-2897 (2021).

[2] Yasui, Y., et al. Nat. Commun. 11, 5925 (2020).

[3] Moya, J., et al. Phys. Rev. Mater. 6, 074201(2022).