Strain-tunable Berry curvature in quasi-two-dimensional chromium telluride
Hang Chi, Yunbo Ou, Tim B. Eldred, Wenpei Gao, Sohee Kwon, Joseph A. Murray, Michael Dreyer, Robert Butera, Alexandre C. Foucher, Haile Ambaye, Jong K. Keum, Alice T. Greenberg, Yuhang Liu, Mahesh R. Neupane, George J. de Coster, Owen Vail, Patrick J. Taylor, P. A. Folkes, Charles Rong, Gen Yin, Roger K. Lake, Frances M. Ross, Valeria Lauter, D. Heiman, Jagadeesh S. Moodera
Abstract
Abstract 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 Cr 2 Te 3 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 Cr 2 Te 3 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 Cr 2 Te 3 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 Cr 2 Te 3 thin films offers new opportunities for topological electronics.