Regularized micromagnetic theory for Bloch points

Area of Science:

• Condensed Matter Physics
• Materials Science
• Theoretical Physics

Background:

• Classical micromagnetic theory assumes fixed magnetization vector length, failing to accurately model Bloch points (BPs) due to effective field divergence.
• Bloch points are magnetic singularities that pose a fundamental challenge to existing micromagnetic models.
• Understanding BP dynamics is crucial for advancing spintronic devices and magnetic data storage.

Purpose of the Study:

• To develop a regularized micromagnetic model capable of describing Bloch point dynamics.
• To incorporate a constraint on magnetization vector length, treating it as an order parameter on an S^3-sphere.
• To extend the applicability of micromagnetic theory to systems with complex magnetic singularities.

Main Methods:

• Developed a regularized micromagnetic model where magnetization vector length is variable but bounded.
• Treated magnetization as an order parameter constrained to an S^3-sphere, aligning with quantum system properties.
• Derived regularized Landau-Lifshitz-Gilbert and Thiele-like equations for steady spin texture motion.

Main Results:

• Successfully modeled the dynamics of magnetic textures containing Bloch points, including domain walls, chiral bobbers, and magnetic dipolar strings.
• Demonstrated the model's ability to handle the complexities arising from Bloch point singularities.
• Validated the regularized equations for describing steady motion under external stimuli.

Conclusions:

• The proposed regularized micromagnetic model provides a robust framework for understanding Bloch point dynamics.
• This approach overcomes the limitations of classical micromagnetics in describing magnetic singularities.
• The findings offer a pathway for more accurate simulations and predictions in magnetic systems with BPs.