Magnetization relaxation and geometric forces in a Bose ferromagnet

Area of Science:

• Quantum physics
• Condensed matter theory
• Bose-Einstein condensates

Background:

• Spin-1/2 Bose gases exhibit complex behaviors involving magnetization and fluid dynamics.
• Existing theories may not fully capture the interplay between spin textures and hydrodynamic properties at various temperatures.

Purpose of the Study:

• To construct a comprehensive hydrodynamic theory for spin-1/2 Bose gases across all temperatures.
• To elucidate the coupling between magnetization and the normal/superfluid components.
• To investigate geometric forces and topological phenomena within these systems.

Main Methods:

• Development of a hydrodynamic theory incorporating spin dynamics.
• Calculation of phenomenological parameters using Bogoliubov approximation and Boltzmann equation (relaxation-time approximation).
• Analysis of the topological Hall effect and its manifestation in collective modes.

Main Results:

• The theory describes the coupling between magnetization and normal/superfluid components.
• Geometric forces arising from spin's adiabatic following of magnetization texture are included.
• The topological Hall effect is linked to Skyrmions and observed in collective modes.
• Magnetization relaxation, fourth-order in spatial gradients, arises from dissipative coupling.

Conclusions:

• The developed hydrodynamic theory provides a framework for understanding spin-1/2 Bose gases.
• It highlights the significance of geometric forces and topological effects in these quantum systems.
• The findings offer insights into magnetization dynamics and relaxation mechanisms.