Structural and magnetic transition induced by bi-axial strain in 2D Fe3GeTe2 monolayer

Two-dimensional materials have been in the spotlight these days because of their technological advantages such as highly tunable flexibility. In particular, van der Waals (VDW) bonded magnetic materials are of great importance as building blocks in spin-driven devices. Fe3GeTe2 is one of highly interesting ferromagnetic VDW materials because it maintains ferromagnetic properties down to a single layer with Curie temperature close to the room temperature. Using first-principles DFT calculations, we comprehensively studied on the coupling of magnetism to structural and electronic properties to find a way to enhance the ferromagnetic stabilities by strain. First, we scrutinize lattice instabilities by investigating the phonon dispersion of strained Fe3GeTe2 mono-layer and found a structural transition at around 7% strain. A linearly enhanced magnetization is observed at below the critical stain. An abrupt magnetization jump concomitant with the structural transition is expected beyond the critical strain. We will discuss the possible atomic-scale origin of the concomitant magnetic and structural transitions drive by the strain.