Equilibrium spin currents and magnetoelectric effect in magnetic nanostructures

TL;DR

This paper investigates the origin and properties of equilibrium spin currents in inhomogeneous ferromagnetic nanostructures, revealing their physical basis and potential for detection via magnetoelectric effects.

Contribution

It introduces a microscopic explanation for equilibrium spin currents and derives their existence from a gauge field approach in magnetic systems.

Findings

Persistent spin currents exist in the ground state of certain magnetic systems.

Equilibrium spin currents can induce measurable electric fields via magnetoelectric effects.

The study provides a framework for understanding and detecting equilibrium spin currents in nanostructures.

Abstract

We discuss the problem of equilibrium spin currents in ferromagnets with inhomogeneous magnetization. Using simple microscopic models we explain the physical origin of equilibrium spin currents. Next we derive the equilibrium spin current from the Hamiltonian with a gauge field associated with local rotations in the spin space. Several examples of magnetic systems are studied in details, and the persistent spin current is found to exist in the ground state of these systems. We also demonstrate the possibility to measure the equilibrium spin current using the magnetoelectrically induced electric field near the ring.