Prototypical topological orbital ferromagnet γ-FeMn

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Mechanics

Background:

• Topological phenomena in materials are typically linked to spin-orbit interaction.
• Orbital magnetization in antiferromagnets often requires specific conditions or strong spin-orbit coupling.
• Understanding the origins of magnetism in complex spin structures is crucial for novel electronic devices.

Purpose of the Study:

• To predict and investigate topological orbital magnetization in γ-FeMn from first principles.
• To explore the role of spin structure topology in generating orbital magnetization.
• To identify the key mechanisms responsible for orbital degeneracy lifting and macroscopic orbital magnetization.

Main Methods:

• First-principles calculations to model the electronic and magnetic properties of γ-FeMn.
• Analysis of spin structure topology and its correlation with orbital magnetization.
• Investigation of the effects of strain, composition, and spin texture on topological properties.

Main Results:

• Prediction of entirely topological orbital magnetization in γ-FeMn, independent of spin-orbit interaction.
• Identification of scalar spin chirality as the primary mechanism for lifting orbital degeneracy.
• Demonstration of prominent macroscopic orbital magnetization in the absence of spin-orbit coupling.
• Observation of a significant topological Hall effect linked to the topological orbital magnetization.

Conclusions:

• γ-FeMn is a prototypical topological orbital ferromagnet due to its noncoplanar spin structure.
• Scalar spin chirality is a key factor in achieving topological orbital magnetization.
• The findings open new avenues for designing materials with strong orbital magnetism without relying on spin-orbit coupling.