Abstract Soft magnetic materials with stable permeability up to hundreds of megahertz (MHz) are urgently needed for integrated transformers and inductors, which are crucial in the more-than-Moore era.However, traditional frequency-stable soft magnetic ferrites suffer from low saturation magnetization and temperature instability, making them unsuitable for integrated circuits.Herein, we fabricate a frequency-stable soft magnetic composite featuring a magnetic vortex structure via cold-sintering, where ultrafine FeSiAl particles are magnetically isolated and covalently Vitamin E bonded by Al2SiO5/SiO2/Fe2(MoO4)3 multilayered heterostructure.This construction results in an ultrastable permeability of 13 up to 1 gigahertz (GHz), relatively large saturation magnetization of 105 Am2/kg and low coercivity of 48 A/m, which we ascribe to the elimination of domain walls associated with almost uniform HYDRATE ME MASQUE single-vortex structures, as observed by Lorentz transmission electron microscopy and reconstructed by micromagnetic simulation.Moreover, the ultimate compressive strength has been simultaneously increased up to 337.
1 MPa attributed to the epitaxially grown interfaces between particles.This study deepens our understanding on the characteristics of magnetic vortices and provides alternative concept for designing integrated magnetic devices.