Modifications of magnetic anisotropy of Fe3GeTe2 by the electric field effect

The Fe3GeTe2 material is the only metallic ferromagnet with a van der Waals layered structure, which has been used as a ferromagnetic electrode in spintronic devices. The tunability of magnetic properties of few-layer Fe3GeTe2 by electrostatic gating is demonstrated in experiments. In this work, we present a theoretical investigation of the electric field effect on the magnetic anisotropy of the Fe3GeTe2 monolayer using the first-principles approach. The calculated magnetic anisotropy energy exhibits strongly oscillating behavior at the electron-doping side, in strong contrast to the hole-doping side. The significant variation of the magnetic anisotropy energy vs electron doping concentration agrees well with experimental results. While the rigid-band approximation works well at the hole-doping side, electron doping induces significant changes in the electronic structure near the Fermi energy. The analysis of the electronic structure shows that the occupation and splitting of the Te(pz)-Fe(dz2) bond states play a critical role in modifying the magnetic anisotropy.