Intercalation-induced New Magnetic Phase in Quasi Two-Dimensional Fe_2.7GeTe₂

Layered quasi-two-dimensional (2D)van der Waals (vdW) magnetic materials gained a great deal of research interest for their exceptional physical properties (layer-dependent magnetism, gate-tunable magnetism, etc.) and promising potential next-generation spintronics applications. Of particular importance, the magnetic behavior of Fe_2.7GeTe₂ (FGT), a vdW itinerant ferromagnet, has been shown to exhibit variable magnetic properties as a function of layer thickness, gate voltage, doping, pressure, etc. However, it is completely unknown how the magnetic properties of FGT are altered upon intercalation with organic molecules. In this work, we show our ability in tuning the magnetic properties of FGT using tetrabutyl ammonium (TBA⁺) via electrochemical intercalation. We find that a new (hard) (ferro) magnetic phase is introduced as well as the magnetic anisotropy is reduced upon the intercalation of FGT with TBA. Our experimental findings suggest that the electron doping upon the intercalation could cause changes in the magnetic properties of FGT. We will present and discuss our in-depth experimental findings resulting from X-ray diffraction, magnetometry, and Raman spectroscopic measurements.