How many bits may fit in a single magnetic dot? XMCD-PEEM evidences the switching of N\'eel caps inside Bloch domain walls

TL;DR

This paper investigates the switching behavior of Neel caps within Bloch domain walls in magnetic dots, providing insights into potential multi-level data storage at nanoscale using XMCD-PEEM imaging.

Contribution

It presents experimental evidence of Neel cap switching inside Bloch domain walls, advancing understanding of magnetic domain wall manipulation for data storage.

Findings

Neel caps can switch within Bloch domain walls.

XMCD-PEEM effectively visualizes Neel cap dynamics.

Insights into multi-level magnetic storage mechanisms.

Abstract

Data storage relies on the handling of two states, called bits. The market of mass storage is currently still dominated by magnetic technology, hard disk drives for the broad public and tapes for massive archiving. In these devices each bit is stored in the form of the direction of magnetization of nanosized magnetic domains, i.e. areas of ferromagnetic materials displaying a uniform magnetization. While miniaturization is the conventional way to fuel the continuous increase of device density, disruptive solutions are also sought. To these pertain in recent years many fundamental studies no longer considering the magnetic domains themselves, but the manipulation of the domain walls (DWs) that separate such domains. Concepts of storage and logic based on the propagation of DWs along lithographically-patterned stripes have been patented, while many fundamental aspects of DW propagation deeply related to condensed matter physics are still hotly debated. If one now considers magnetic dots of submicrometer dimensions, the magnetization has a tendency to curl along the outer edges of the nanostructure to close its magnetic flux and thereby reduce its magnetostatic energy. Then both domains and DWs of well-defined geometries arise, whose combined manipulation has been proposed as a multilevel magnetic storage scheme...