Strain-Induced Interlayer Magnetic Coupling Spike of the Two-Dimensional van der Waals Material Fe₅GeTe₂

A stronger interlayer magnetic coupling (ILMC) can openup newopportunities in spintronic devices. Numerous publications have demonstratedthat ILMC is continuously evolving, even in the context of magneticphase change. Here, we observe an extraordinary discontinuous transition(ILMC spike) in a two-dimensional (2D) van der Waals (vdW) material,Fe5GeTe2 (F5GT). The ILMC spikes from 1.15 to12.79 meV/f.u when a 3% in-plane biaxial strain is applied. Additionally,the applied in-plane strain significantly enhances the magnetic anisotropyenergy (MAE) of the system, triggering a sharp transition betweenthe in-/off-plane configurations in multilayer F5GT.