# Unidirectional spin-wave channeling along magnetic domain walls of Bloch type

## TL;DR

This paper investigates nonreciprocal spin-wave propagation along Bloch-type magnetic domain walls using micromagnetic simulations, revealing conditions for unidirectional spin-wave channeling due to dynamic dipolar interactions.

## Contribution

It demonstrates the strong nonreciprocity of spin-waves in Bloch walls and analyzes their behavior in both single walls and arrays, highlighting the potential for unidirectional spin-wave channels.

## Key findings

- Spin-waves in Bloch walls exhibit strong nonreciprocity due to dipolar interactions.
- Arrays of domain walls develop complex spin-wave band structures.
- Under certain conditions, spin-wave propagation becomes unidirectional within individual walls.

## Abstract

From the pioneering work of Winter [Phys. Rev. 124, 452 (1961)], a magnetic domain wall of Bloch type is known to host a special wall-bound spin-wave mode, which corresponds to spin-waves being channeled along the magnetic texture. Using micromagnetic simulations, we investigate spin-waves travelling inside Bloch walls formed in thin magnetic media with perpendicular-to-plane magnetic anisotropy and we show that their propagation is actually strongly nonreciprocal, as a result of dynamic dipolar interactions. We investigate spin-wave non-reciprocity effects in single Bloch walls, which allows us to clearly pinpoint their origin, as well as in arrays of parallel walls in stripe domain configurations. For such arrays, a complex domain-wall-bound spin-wave band structure develops, some aspects of which can be understood qualitatively from the single-wall picture by considering that a wall array consists of a sequence of up/down and down/up walls with opposite non-reciprocities. Circumstances are identified in which the non-reciprocity is so extreme that spin-wave propagation inside individual walls becomes unidirectional.