Domains and domain walls in amorphous ferrimagnetic alloys across the compensation temperature
Phys. Rev. B 114, 034422 – Published 21 July, 2026
DOI: https://doi.org/10.1103/y432-39hp
Abstract
Rare-earth transition-metal alloys are widely investigated as model ferrimagnetic systems for ultrafast magnetization dynamics and domain wall motion. Here, we investigate changes in the local magnetization and domain wall structure of GdFeCo thin films across the magnetic compensation temperature using nitrogen vacancy magnetometry. We find that the magnetic compensation temperature varies by up to 15 K in regions spaced by hundreds of microns in a single film due to the inhomogeneous composition of the alloy. We map the profile of domain walls across the compensation temperature in Pt/GdFeCo/Ta, Pt/GdFeCo/Pt, and Cu/GdFeCo/Pt trilayers. In Pt/GdFeCo/Ta, the domain walls are of mixed left Néel and Bloch-type with widths between 20 and 50 nm below compensation, and change towards Bloch-type with widths between 50 and 70 nm at and above compensation. In Pt/GdFeCo/Pt (Cu/GdFeCo/Pt), the domain wall width is larger, and the domain walls are of Bloch (mixed Bloch-right Néel) type, consistent with changes in perpendicular magnetic anisotropy and interfacial Dzyaloshinskii-Moriya interaction in these structures. Our results indicate the presence of a magnetic compensation gradient throughout the thickness of GdFeCo when interfaced with Ta, due to a higher oxygen concentration at this interface. This vertical compensation gradient gives rise to compensation planes through the thickness of the sample, resulting in an anomalous magnetic stray field profile of domain walls at the compensation temperature. Our results provide insight into the micromagnetic structure of domain walls and magnetization distribution in ferrimagnetic alloys, with applications in the engineering of ferrimagnetic spintronic devices.
