Interior and Edge Magnetization in Thin Exfoliated CrGeTe₃ Films

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Semiconducting van der Waals ferromagnets are promising for spintronics.
• Chromium germanium telluride (CrGeTe3) exhibits magnetism even at the two-layer limit.
• A detailed understanding of CrGeTe3's thickness-dependent magnetic properties is needed.

Purpose of the Study:

• To comprehensively analyze the thickness-dependent magnetization of CrGeTe3.
• To correlate global magnetic behavior with local domain structures.
• To establish a magnetization state diagram for CrGeTe3 films.

Main Methods:

• Scanning SQUID-on-tip (SOT) microscopy at 4.2 K.
• Transport measurements of CrGeTe3/NbSe2 heterostructures.
• Combining local SOT imaging with global transport data.

Main Results:

• A thickness-dependent magnetization state diagram for CrGeTe3 was established.
• Films thicker than 10 nm showed no zero-field magnetic memory.
• Films below 10 nm exhibited hard ferromagnetism.
• Unique edge magnetism was observed using SOT microscopy, distinct from interior magnetism.

Conclusions:

• CrGeTe3's magnetic properties are strongly dependent on film thickness.
• The critical thickness of 10 nm differentiates magnetic memory behavior.
• Edge magnetism in CrGeTe3 presents novel characteristics compared to bulk properties.