Strain-tunable Berry curvature in quasi-two-dimensional chromium telluride.

Magnetic transition metal chalcogenides form an emerging platform for exploring spin-orbit driven Berry phase phenomena owing to the nontrivial interplay between topology and magnetism. Here we show that the anomalous Hall effect in pristine Cr₂Te₃ thin films manifests a unique temperature-dependent sign reversal at nonzero magnetization, resulting from the momentum-space Berry curvature as established by first-principles simulations. The sign change is strain tunable, enabled by the sharp and well-defined substrate/film interface in the quasi-two-dimensional Cr₂Te₃ epitaxial films, revealed by scanning transmission electron microscopy and depth-sensitive polarized neutron reflectometry. This Berry phase effect further introduces hump-shaped Hall peaks in pristine Cr₂Te₃ near the coercive field during the magnetization switching process, owing to the presence of strain-modulated magnetic layers/domains. The versatile interface tunability of Berry curvature in Cr₂Te₃ thin films offers new opportunities for topological electronics. Chromium tellurides are a particularly promising family of quasi-2D magnetic materials; towards the single van der Waals layer limit, they preserve magnetic ordering, some even above room temperature, and exhibit a variety of intrinsic topological properties. Here, Hang Chi, Yunbo Ou and co-authors demonstrate a strain tunable Berry curvature induced reversal of the anomalous Hall effect in Cr₂Te₃. [ABSTRACT FROM AUTHOR]