Anomalous Hall effect arising from noncollinear antiferromagnetism

Area of Science:

• Condensed Matter Physics
• Materials Science
• Solid-State Physics

Background:

• The anomalous Hall effect (AHE) in ferromagnetic conductors arises from mechanisms beyond the Lorentz force, persisting without external magnetic fields.
• Conventionally, anomalous Hall conductivity is presumed to scale directly with magnetization.

Purpose of the Study:

• To investigate the relationship between anomalous Hall conductivity and magnetization in ferromagnetic materials.
• To challenge the established assumption of direct proportionality between anomalous Hall conductivity and magnetization.
• To predict the anomalous Hall conductivity of manganese iridium (Mn3Ir), a high-temperature antiferromagnet used in spin-valve devices.

Main Methods:

• Utilizing symmetry arguments to analyze the underlying physics of the anomalous Hall effect.
• Performing first-principles electronic structure calculations to determine material properties.

Main Results:

• The study counters the conventional assumption that anomalous Hall conductivities are proportional to magnetization.
• First-principles calculations predict a significant anomalous Hall conductivity for Mn3Ir.
• Mn3Ir, an antiferromagnet, exhibits a large anomalous Hall conductivity.

Conclusions:

• The proportionality between anomalous Hall conductivity and magnetization is not universally applicable.
• Antiferromagnetic materials like Mn3Ir can possess substantial anomalous Hall conductivity.
• This finding has implications for the design and application of spintronic devices.