Reversible strain-induced magnetic phase transition in a van der Waals magnet

Mechanical deformation of a crystal can have a profound effect on its physical properties. For instance, even small modifications of bond geometry can completely change the size and sign of magnetic-exchange interactions, and thus the magnetic ground state. Here, we report drastic strain tuning of the magnetic properties of the A-type layered antiferromagnetic semiconductor CrSBr. This is achieved by designing a strain device which can apply continuous, in-situ uniaxial tensile strain approaching several percent to 2D materials at cryogenic temperatures. Using this apparatus, we realize a reversible strain-induced antiferromagnetic to ferromagnetic phase transition at zero magnetic field and strain control of the out-of-plane spin canting process. First-principles calculations reveal that the tuning of the in-plane lattice constant strongly modifies the interlayer magnetic exchange interaction, which changes sign at the critical strain. Our work creates new opportunities for harnessing the strain control of magnetism and other electronic states in low dimensional materials and heterostructures.