Nanomechanical Characterization of an Antiferromagnetic Topological Insulator

Project Summary: Despite extensive research on the transport properties of magnetic phase transitions in MnBi2Te4, the first intrinsic magnetic topological insulator, its mechanical characteristics and magneto-mechanical coupling remain largely unexplored. To address this gap, the Deshpande group at the University of Utah, in collaboration with the Wang group at UCLA and the 2DCC, investigated the magneto-mechanical properties of MnBi2Te4 using nanoelectromechanical systems (NEMS). They fabricated MnBi2Te4 thin flakes into NEMS resonators, enabling them to probe the material's intrinsic magnetism via magnetostrictive coupling. By analyzing shifts in mechanical resonance frequency under varying magnetic fields, the study revealed spin-flop transitions corresponding to antiferromagnetic (AFM), canted antiferromagnetic (CAFM), and ferromagnetic (FM) phases. A magnetostrictive model was then applied to correlate these frequency shifts with spin-canting states, allowing for the extraction of magnetostrictive coefficients. This work demonstrates a valuable NEMS-based approach for investigating magnetic phase transitions and magnetoelastic properties in antiferromagnetic topological insulators. The findings enhance our understanding of spin-lattice coupling in these materials.
Published in Nano Letters 25, 973 (2025). DOI: 10.121/acs.nanolett.4c04086
2DCC Role: This research resulted from a close collaboration between 2DCC and two user projects of Prof. Wang and Prof. Deshpande. The 2DCC’s ability of growing high-quality MnBi2Te4 crystals made this impactful work possible.