Spin-hedgehog-derived electromagnetic effects in itinerant magnets

Area of Science:

• Condensed Matter Physics
• Materials Science
• Magnetism

Background:

• Itinerant magnets exhibit complex magnetic textures due to Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions and higher-order spin couplings.
• Noncoplanar magnetic textures lead to a finite Berry phase in conduction electrons, resulting in the topological Hall effect.
• Magnetic hedgehog lattices, arrays of magnetic anti- and monopoles, have been recently observed in B20-type compounds.

Purpose of the Study:

• To investigate the formation of magnetic hedgehog lattices in three-dimensional itinerant magnets using an effective spin model.
• To explore the ground state spin configuration in noncentrosymmetric crystal structures.
• To analyze the topological Hall conductivity and its relation to the spin hedgehog lattice and the magneto-optic Kerr effect.

Main Methods:

• Utilized an effective spin model incorporating bilinear-biquadratic exchange interactions.
• Employed a neural-network-based approach for exploring ground state spin configurations, contrasting with traditional Monte Carlo simulations.
• Investigated the coupling between the spin hedgehog lattice and conduction electrons to understand topological phenomena.

Main Results:

• Successfully modeled the formation of a magnetic hedgehog lattice in a three-dimensional itinerant magnet.
• Demonstrated the association of topological Hall conductivity with nonzero scalar spin chirality due to the spin hedgehog lattice.
• Provided evidence for the magneto-optic Kerr effect in the context of these magnetic structures.

Conclusions:

• The study highlights the efficacy of neural network methods in exploring complex magnetic ground states.
• The findings offer a deeper understanding of topological phenomena, including the topological Hall effect and scalar spin chirality, in itinerant magnets.
• The research establishes a link between magnetic hedgehog lattices and observable effects like the magneto-optic Kerr effect, paving the way for future spintronic applications.