Ultrafine FeCo Nanoparticles Isolated by Ultrathin Dielectric Shells for Microwave Application

Abstract

Low-dimensional soft magnetic materials are technologically important for miniaturization of magnetic devices. It is, however, challenging to maintain ferromagnetic response in nanosized magnetic material. In this work, ultrafine FeCo nanoparticles have been prepared by reactive pulsed laser deposition, which can be exchange coupled through ultrathin dielectric shells, even though their diameters are far below the superparamagnetic blocking limit. This unique core/shell structure guarantees ferromagnetic coupling and insulation of neighboring magnetic nanoparticles simultaneously. The nanoparticle film exhibits large saturation magnetization of 1.13 T, high electrical resistivity of 4200 μΩ·cm, maximum permeability of 120, a cutoff frequency of 1.7 GHz, and it is a promising material for microwave application.

Ultrafast Particle Size Reduction of Fe73.9Si15.5Cu1Nb3B6.6 by High-Energy Milling: Nb2O5 as a Marker of Permeability Enhancement and Magnetic Hardening

“…The major role of soft magnetic materials is to produce a stable high-density magnetic flux in a specified spatial region with polarization switches at low applied magnetic field values . Their applications encompass an enormous range of interdisciplinary technological purposes as highly efficient microwave absorbers, − sensor microwires, , hard/soft magnetic nanocomposites for improved permanent magnets, , three-dimensional nano-engineered composite multilayers, nanowires for magnetic-sensing devices, , polymer-coated multicore nanoparticles for sensing and drug delivery, microwires for high heating efficiency in magnetic hyperthermia, health monitoring, , and soft magnetic ferrites for excellent diagnostic imaging applications . Therefore, a continuous and necessary demand of technological development exists with the objective of improving their functional properties by tuning the particle size, morphology, and chemical stability. , …”