Screw dislocations in cubic chiral magnets

TL;DR

This paper explores the structure and properties of screw dislocations in cubic chiral magnets, revealing their universal far-field behavior, diverse core structures, and potential for manipulation via spin currents.

Contribution

It provides a detailed analysis of screw dislocation cores in cubic chiral magnets, including the classification by integer strength and the discovery of various core configurations.

Findings

Dislocations have a universal far-field classified by an integer strength.

Core structures can be smooth or singular, including chains of Bloch points.

Dislocations carry a finite skyrmion charge, enabling manipulation by spin currents.

Abstract

Helimagnets realize an effective lamellar ordering that supports disclination and dislocation defects. Here, we investigate the micromagnetic structure of screw dislocation lines in cubic chiral magnets using analytical and numerical methods. The far field of these dislocations is universal and classified by an integer strength $\nu$ that characterizes the winding of magnetic moments. We demonstrate that a rich variety of dislocation-core structures can be realized even for the same strength $\nu$. In particular, the magnetization at the core can be either smooth or singular. We present a specific example with $\nu = 1$ for which the core is composed of a chain of singular Bloch points. In general, screw dislocations carry a non-integer but finite skyrmion charge so that they can be efficiently manipulated by spin currents.