Chiral charge transport induced by a tunable tilt of Weyl nodes in van der Waals topological magnets

Weyl semimetals exhibit unique electromagnetic responses and present a promising platform for spintronic applications, particularly when nontrivial electronic band topologies are involved. Here, we demonstrate the on-demand manipulation of the electronic bandstructure through the intake and release of ionic hydrogen (H⁺) — a process we found to induce conversions among Weyl states with different Weyl node tilts and spin textures [1]. We show that the presence of H⁺ generates distinctive enhanced chirality-directed conduction channels in the van der Waals Weyl ferromagnet MnSb₂Te₄. Upon partial hydrogen removal, the system becomes a different kind of a ferromagnet in which (1) magnetic anisotropy is altered and (2) the Curie temperature T_C is doubled — both experimental findings rationalized by our DFT calculations. These changes modify key features of the topological band structure, consistent with model calculations of the Type-I tilted Weyl nodes that include the ratio of the internode/intranode scattering rates. Our experiments show that as-grown MST (FM 1) transitions from field-symmetric MR to field-antisymmetric MR in hydrogen-altered FM 2. Angle (φ) resolved in-plane-field magnetotransport measurements indicate that FM MST is a Type I WSM with oppositely tilted Weyl cones, exhibiting a giant field-antisymmetric planar Hall effect (PHE). Additionally, in-plane transport exhibits φ-chirality, with a large chirality metric χ^±φ, and a tunable φ-chiral hysteresis loop associated with the out-of-plane Berry curvature. We will present experimental results on hydrogen-induced Weyl node modification and chirality amplification of transport coefficients in FM MST, along with the corresponding magnetic anisotropy changes. A putative quantization of planar Hall transport coefficients will be discussed.



[1] A. N. Tamanna, A. Lakra, X. Ding, E. Buzi, K. Park, K. Sobczak, H. Deng, G. Sharma, S. Tewari, L. Krusin-Elbaum, Nature Comms., October (2024); https://doi.org/ 10.1038/s41467-024-53319-w.