Gate-tunable room-temperature ferromagnetism in two-dimensional Fe₃GeTe₂

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Advancements in nano-electronic devices rely heavily on materials research, particularly in magnetic thin films for spintronics.
• Van der Waals crystals offer atomic thinness, chemical stability, and gate tunability, making them promising for novel electronic applications.
• Previous studies demonstrated two-dimensional (2D) ferromagnetic order in insulating materials like Cr2Ge2Te6 and CrI3 at low temperatures.

Purpose of the Study:

• To fabricate devices and isolate monolayers of the metallic magnet Fe3GeTe2 for magnetotransport studies.
• To investigate the persistence of itinerant ferromagnetism in 2D Fe3GeTe2 and its magnetic properties.
• To explore the effect of ionic gating on the ferromagnetic transition temperature (Tc) of 2D Fe3GeTe2.

Main Methods:

• Development of a specialized device fabrication technique.
• Isolation of atomically thin monolayers from layered Fe3GeTe2.
• Measurement of magnetotransport properties and the influence of ionic gating on Tc.

Main Results:

• Itinerant ferromagnetism is confirmed to persist in Fe3GeTe2 down to the monolayer level, exhibiting out-of-plane magnetocrystalline anisotropy.
• The ferromagnetic transition temperature (Tc) of pristine Fe3GeTe2 monolayers is suppressed compared to the bulk value (205 K).
• Ionic gating significantly enhances Tc, achieving room-temperature ferromagnetism in 2D Fe3GeTe2, surpassing the bulk Tc.

Conclusions:

• Room-temperature ferromagnetism is achievable in 2D Fe3GeTe2 through ionic gating.
• The gate-tunable ferromagnetism in this atomically thin van der Waals material opens avenues for voltage-controlled magnetoelectronics.
• This research highlights the potential of 2D van der Waals magnets for next-generation spintronic and electronic devices.