# Magnetic Domain Walls as Hosts of Spin Superfluids and Generators of Skyrmions

## TL;DR

This paper demonstrates that magnetic domain walls can host spin superfluids with unique topological properties, enabling skyrmion generation, magnon manipulation, and spin transport control, supported by theoretical and numerical analysis.

## Contribution

It introduces the concept of spin superfluidity within magnetic domain walls and explores its topological properties and potential for skyrmion and magnon control.

## Key findings

- Domain walls can host spin superfluids with topological features.
- Phase slips in the superfluid create and annihilate skyrmions, conserving skyrmion charge.
- Emergent magnetic flux along the domain wall enables magnon manipulation.

## Abstract

A domain wall in a magnet with easy-axis anisotropy is shown to harbor spin superfluid associated with its spontaneous breaking of the U(1) spin-rotational symmetry. The spin superfluid is shown to have several topological properties, which are absent in conventional superfluids. First, the associated phase slips create and destroy skyrmions to obey the conservation of the total skyrmion charge, which allows us to use a domain wall as a generator and detector of skyrmions. Secondly, the domain wall engenders the emergent magnetic flux for magnons along its length, which are proportional to the spin supercurrent flowing through it, and thereby provides a way to manipulate magnons. Thirdly, the spin supercurrent can be driven by the magnon current traveling across it owing to the spin transfer between the domain wall and magnons, leading to the magnonic manipulation of the spin superfluid. The theory for superfluid spin transport within the domain wall is confirmed by numerical simulations.