The influence of structural disorder on magnetic domain formation in perpendicular anisotropy thin films

TL;DR

This study investigates how structural disorder, controlled by sputtering pressure, affects magnetic domain formation and microstructure in perpendicular anisotropy Co/Pt multilayer films, revealing a transition from gas-like to liquid-like domain arrangements.

Contribution

It demonstrates the impact of deposition-induced structural and chemical disorder on magnetic domain morphology and provides insights into domain wall behavior in disordered magnetic films.

Findings

Low pressure samples show gas-like magnetic domain distribution.

Higher pressure samples exhibit short-range liquid-like order.

Increased disorder leads to magnetic void regions confining domains.

Abstract

Using a combination of resonant soft x-ray scattering, magnetometry, x-ray reflectivity and microscopy techniques we have investigated the magnetic properties and microstructure of a series of perpendicular anisotropy Co/Pt multilayer films with respect to structural disorder tuned by varying the sputtering deposition pressure. The observed magnetic changes in domain size, shape and correlation length originate from structural and chemical variations in the samples, such as chemical segregation and grain formation as well as roughness at the surface and interfaces, which are all impacted by the deposition pressure. For low pressure samples we find evidence of a random "gas-like" distribution of magnetic domains, while in the higher pressure samples the domain structure exhibits only short range "liquid-like" positional ordering. The structural and chemical disorder induced by the higher deposition pressure first leads to an increase in the number of magnetic point defects that limit free domain wall propagation. Then, as the sputtering pressure is further increased, the domain wall energy density is lowered due to the formation of local regions with reduced magnetic moment, and finally magnetically void regions appear that confine the magnetic domains and clusters, similar to segregated granular magnetic recording media.