Adiabatic Pumping of Orbital Magnetization by Spin Precession

Abstract: We propose adiabatic pumping of orbital magnetization driven by coherent spin precession, facilitating the rectification of this precession. The orbital magnetization originates from the adiabatic evolution of valence electrons with a topological bulk contribution expressed as a Chern-Simons form. When the precession cone angle of spin $\mathbf{S}$ is small, the resulting magnetization is proportional to $\mathbf{S}\times \dot{\mathbf{S}}$, contributing to the magnon Zeeman effect. With a large cone angle, the magnetization can reach its natural unit, $e/T$, in an antiferromagnetic topological insulator with $e$ as the elementary charge and $T$ as the precession period. This significant magnetization is related to the global properties of the electronic geometric phases in the parameter space spanned by $\mathbf{S}$ and momentum $\mathbf{k}$. When the pumped magnetization is inhomogeneous, induced by spin textures or electronic topological phase domains, a dissipationless charge current is also pumped. At last, we discuss the boundary contributions from the spin-driving edge states, which are intricately linked to the gauge-dependent quantum uncertainty of the Chern-Simons form.