Scaling the Altermagnet GdAlSi beyond the Monolayer Limit.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Altermagnets are a novel class of magnetic materials with zero net magnetization and significant spin-based phenomena, making them promising for spintronics.
• Scaling down magnetic materials to the nanoscale is crucial for practical spintronic applications, but experimental exploration remains limited.
• Previous studies on GdAlSi Weyl altermagnet films revealed symmetry breaking and thickness-dependent properties down to the monolayer limit.

Purpose of the Study:

• To investigate the potential for further miniaturization of GdAlSi beyond the monolayer.
• To explore the spintronic properties of 1/2 monolayer GdAlSi films.
• To assess the feasibility of using 1/2 monolayer GdAlSi as a building block for two-dimensional (2D) spintronic materials.

Main Methods:

• Epitaxial growth of 1/2 monolayer GdAlSi films.
• Characterization of structural and magnetic properties.
• Electrical transport measurements, including magnetoresistance and anomalous Hall effect.

Main Results:

• Successful fabrication of 1/2 monolayer GdAlSi films with nearly compensated magnetic moments.
• Observation of semiconducting behavior in 1/2 monolayer GdAlSi, contrasting with metallic monolayer and bulk.
• Demonstration of colossal negative magnetoresistance exceeding that of the monolayer by over an order of magnitude.
• Anomalous Hall effect in 1/2 monolayer GdAlSi conforming to the universal scaling relation for magnetic semiconductors.

Conclusions:

• The structure of GdAlSi enables miniaturization to 1/2 monolayer, serving as a fundamental unit for 2D spintronic materials.
• 1/2 monolayer GdAlSi exhibits unique semiconducting properties and enhanced magnetoresistance, surpassing monolayer performance.
• Seamless integration with silicon suggests high potential for developing ultracompact spintronic devices.