Anomalous Hall Effect in Type IV 2D Collinear Magnets

Area of Science:

• Condensed Matter Physics
• Materials Science
• Spintronics

Background:

• Established magnetic phases include ferromagnets, antiferromagnets, and altermagnets.
• Two-dimensional (2D) materials offer unique platforms for exploring novel magnetic phenomena.

Purpose of the Study:

• To identify and characterize a previously unrecognized class of 2D collinear magnetic phase.
• To establish the symmetry criteria for this new magnetic phase.
• To explore its potential for unconventional spintronic applications.

Main Methods:

• Spin layer group analysis to derive symmetry criteria.
• First-principles calculations to screen candidate materials.
• Prototype studies using monolayer Hf2S to demonstrate key properties.

Main Results:

• Identification of a type IV 2D collinear magnetic phase with spin-degenerate bands in the nonrelativistic limit.
• Observation of time-reversal symmetry-breaking responses, including the anomalous Hall effect (AHE), despite zero net magnetization.
• Demonstration of AHE driven by spin-polarized and spin-neutral currents, with a symmetry-protected persistent spin texture in monolayer Hf2S.

Conclusions:

• The discovery expands the classification of magnetic phases in 2D materials.
• This new phase offers novel avenues for realizing unconventional spintronic functionalities.
• Type IV 2D collinear magnets represent a promising area for future research and device development.