Observation of Bloch-point domain walls in cylindrical magnetic nanowires

TLDR

Topological protection safeguards quantum and nanoscale systems, and in magnetism the Bloch‑point—a local vanishing of magnetization—has been theoretically predicted for decades but never experimentally observed. We experimentally confirm Bloch‑points inside domain walls of cylindrical magnetic nanowires using surface and transmission XMCD‑PEEM microscopy, enabling future studies of their predicted dynamic phenomena.

Abstract

Topological protection is an elegant way of warranting the integrity of quantum and nanosized systems. In magnetism one example is the Bloch-point, a peculiar object implying the local vanishing of magnetization within a ferromagnet. Its existence had been postulated and described theoretically since several decades, however it has never been observed. We con rm experimentally the existence of Bloch points, imaged within domain walls in cylindrical magnetic nanowires, combining surface and transmission XMCD-PEEM magnetic microscopy. This opens the way to the experimental search for peculiar phenomena predicted during the motion of Bloch-point-based domain walls.