Magnetic Phase Transition and Magneto-Mechanical Coupling in Layered CrSBr Probed by Nano-Optomechanical Resonators

Recent progress in 2D magnetic materials represents an emerging research frontier. For example, various types of novel magnetic orderings at 2D limit have been discovered, including collinear ferromagnets/antiferromagnets, noncollinear spin textures, quantum spin liquid and magnetic topological insulators [1]. In addition, their spin excitations and the coupling with other quasiparticles are expected to be substantially enhanced due to the weak dielectric screening at the 2D limit [2,3]. In contrast to the abundant optical and electrical studies, the thermodynamic and mechanical properties for these rich quantum phases and unique coupling physics are important yet missing.<br/>In this talk, I will present our study of the thermodynamic and mechanical properties in van der Waals magnets using nano-optomechanical resonators. In particular we have successfully developed nanoscale resonators based on target ultrathin magnetic membranes CrSBr, in which mechanical properties of the membrane can be electrically driven and sensed by precise optical interferometry. The nanomechanical response contains critical thermodynamic and information in magnetostriction in different spin orderings. Our work advances the understanding of magneto-mechanical coupling in 2D magnetic materials and enables new opportunities for coupling light, magnetism, and mechanics at the nanoscale.<br/><br/>[1] C. Gong and X. Zhang, <i>Science</i> 363, 706 (2019).<br/>[2] M. Gibertini, M. Koperski, A. F Morpurgo, and K. S. Novoselov, <i>Nat. Nanotechnol.</i> 14, 408 (2019).<br/>[3] H. Kurebayashi, J. H. Garcia, S. Khan, J. Sinova, and S. Roche, <i>Nat. </i><i>Rev. Phys.</i> 4, 150 (2022).