Coordination Thermodynamic Control of Magnetic Domain Configuration Evolution toward Low-Frequency Electromagnetic Attenuation

Abstract

The precise tuning of magnetic nanoparticle size and spacing directly influences the alignment of intrinsic magnetic moments and magnetic domains, thereby shaping magnetic properties. However, the dynamic evolution mechanisms of magnetic domain configurations in relation to electromagnetic (EM) attenuation behavior remain poorly understood. To address this gap, a thermodynamically controlled periodic coordination strategy is proposed to achieve precise modulation of magnetic nanoparticle spacing. This approach unveils the evolution of magnetic domain configurations, progressing from individual to coupled and ultimately to crosslinked domain configurations. A unique magnetic coupling phenomenon surpasses the Snoek limit in low-frequency range, which is observed through micromagnetic simulation. The crosslinked magnetic configuration achieves effective low-frequency EM wave absorption at 3.68 GHz, encompassing nearly the entire C-band. This exceptional magnetic interaction significantly enhances radar camouflage and thermal insulation properties. Additionally, a robust gradient metamaterial design extends coverage across the full band (2-40 GHz), effectively mitigating the impact of EM pollution on human health and environment. This comprehensive study elucidates the evolution mechanisms of magnetic domain configurations, addresses gaps in dynamic magnetic modulation, and provides novel insights for the development of high-performance, low-frequency EM wave absorption materials.

Keywords: Electrical/magnetic coupling; Low-frequency electromagnetic wave absorption; Magnetic domain configuration; Multifunction; Thermodynamically controlled coordination strategy.

Fig. 1

Magnetic response modulation strategy for coordination thermodynamically controlled NF@NCA composites

Fig. 2

Morphological and physicochemical characterization of NF@NCA composites. SEM images of a–b NCA and c–d NF@NCA-3. e–j HRTEM images of NF@NCA-3. k TEM and EDS images of NF@NCA-3. l XRD pattern of NF@NCA composites. m Ni 2p XPS spectra, n O 1s XPS spectra of NF@NCA-3

Fig. 3

EMWA performance of NF@NCA composites. 3D RL mappings, 2D EAB mappings, and 3D impedance matching diagrams for a–a" NF@NCA-1, b–b" NF@NCA-2, c–c" NF@NCA-3, and d–d" NF@NCA-4. e Smith charts at a thickness of 4.69 mm. f Attenuation constants of NF@NCA composites. g Complex permittivity of NCA and NF@NCA composites

Fig. 4

Dielectric loss mechanisms of NF@NCA composites. a Real part and b imaginary part of permittivity, c dielectric loss tangent, d polarization percentage, e–h polarization relaxation behavior of NF@NCA composites. i DOS for Ni and NF alloy. j Work function of the NF alloy (111) plane. k Schematic of the built-in electric field. l Electric field loss. m Power loss density. n Electron hologram with TEM inset and o charge density mapping

Fig. 5

Magnetic loss mechanism. a Real part and b imaginary part of complex permeability. c Magnetic loss tangent. d Eddy current loss value. e Room-temperature magnetic hysteresis loops of NF@NCA composites. f Off-axis electron holograms of sliced NF@NCA-3 and g corresponding magnetic flux lines. Micromagnetic simulations of h1 individual, h2 coupled, and h3 crosslinked magnetic configurations

Fig. 6

EM loss mechanism and multifunctional performance exploration. a EMWA mechanism of NF@NCA composites. b Radar stealth properties of NF@NCA composites. c Thermal insulation performance of NF@NCA-3. d Gradient metamaterial design showcasing EMW attenuation properties for Bluetooth devices