Symmetry-Enabled Coexistence of Linear and Nonlinear Hall Responses in Mn2NSF Janus MXene

Abstract

The controlled realization of simultaneous linear and nonlinear Hall responses within a single material platform remains a central challenge in quantum geometric transport. Here, using first-principles density functional theory in conjunction with maximally localized Wannier function analysis, we investigate the Janus MXene Mn2NSF as a two-dimensional noncentrosymmetric magnetic system capable of hosting coexisting anomalous and nonlinear Hall effects. We demonstrate that Mn2NSF is a dynamically and thermally stable half-metallic ferromagnet with in-plane magnetic anisotropy. The asymmetric surface functionalization in Mn2N MXene induces the breaking of intrinsic inversion and horizontal mirror symmetry. These generate finite Berry curvature and a pronounced Berry curvature dipole. Spin–orbit coupling opens local gaps at conduction-band crossings, producing momentum-localized geometric hotspots near the K and K′ points. As a result, the system exhibits sizable anomalous Hall conductivity near the Fermi level and a strongly energy-dependent nonlinear Hall response. Further, we find that biaxial strain provides an efficient tuning parameter, as compressive strain enhances interband quantum geometric tensor contributions, while tensile strain amplifies the Berry curvature dipole. These findings establish Mn2NSF Janus MXene as a versatile platform for strain-engineered linear and nonlinear quantum transport in spin–orbitronic applications.