Hydrogen-tuned charge transport in a van der Waals antiferromagnet MnSb₂Te₄ with antisite disorder

Van der Waals antiferromagnets have recently emerged as materials with unique electronic and magnetic properties, making them promising candidates for next-generation electronic devices. Among these materials, MnSb₂Te₄ (MST) stands out for its promising exotic electronic states and tunable transport properties. Due to easy formation of Mn and Sb interchange (antisite) defects MST can be grown as an antiferromagnet (AFM) or a ferromagnet (FM). Here we demonstrate that a more disordered FM MST can be converted into a robust AFM MST with the same Néel temperature T_N ≅ 18.5 K by injecting ionic hydrogen [1]. The change in magnetic anisotropy, seen in the magnetization measurements and confirmed by our density functional theory (DFT) calculations, reduces the two characteristic AFM fields in the converted MST — a spin-flop transition field H₁ at which the system is driven into a canted AFM state and field H₂ at which the system becomes aligned with the external field — but maintains the ratio H₁ / H₂ ≅ 2, allowing for easier tunability into a fully aligned FM state. We show that in both AFM systems, the in-plane longitudinal conductivity is field-linear and there is a large planar Hall effect, both characteristics of a Weyl semimetal. The results of the angularly resolved in-plane transport measurements and the effects of disorder in as-grown and converted AFM MST will be presented and the implications for potential applications in tunable spintronic devices will be discussed.