Key Takeaways & Executive Findings
- •• A novel multifunctional carbon foam with nanoscale chiral magnetic heterostructures is constructed, in which the interconnection network provides strong conduction loss. • The interfacial polarization loss induced by the FeNi-carbon interfaces is confirmed by density functional theory calculations, and magnetic pinning and coupling effects are revealed by micromagnetic simulation. • The composite foam exhibits an ultrabroad effective absorption bandwidth (EAB) of 14 GHz and a C-band EAB of 4 GHz, achieving full C-band coverage. • This study provides guidelines for designing chiral-dielectric-magnetic trinity composites to achieve broadband microwave absorption in low frequency.
Abstract
The construction of carbon nanocoil (CNC)-based chiral-dielectric-magnetic trinity composites is considered as a promising approach to achieve excellent low-frequency microwave absorption. However, it is still challenging to further enhance the low frequency microwave absorption and elucidate the related loss mechanisms. Herein, the chiral CNCs are first synthesized on a three-dimensional (3D) carbon foam and then combined with the FeNi/NiFe2O4 nanoparticles to form a novel chiral-dielectric-magnetic trinity foam. The 3D porous CNC-carbon foam network provides excellent impedance matching and strong conduction loss. The formation of the FeNi-carbon interfaces induces interfacial polarization loss, which is confirmed by the density functional theory calculations. Further permeability analysis and the micromagnetic simulation indicate that the nanoscale chiral magnetic heterostructures achieve magnetic pinning and coupling effects, which enhance the magnetic anisotropy and magnetic loss capability. Owing to the synergistic effect between dielectricity, chirality, and magnetism, the trinity composite foam exhibits excellent microwave absorption performance with an ultrabroad effective absorption bandwidth (EAB) of 14 GHz and a minimum reflection of loss less than −50 dB. More importantly, the C-band EAB of the foam is extended to 4 GHz, achieving the full C-band coverage. This study provides further guidelines for the microstructure design of the chiral-dielectric-magnetic trinity composites to achieve broadband microwave absorption.
1. Introduction
Electronic devices and systems based on the fifth-generation (5G) technologies bring great convenience to daily life. However, the electromagnetic wave interference/radiation is also becoming a potential threat [1–3]. Multitudinous microwave absorption materials with excellent absorption performance have been developed, most of which exhibit wide effective absorption bandwidth (EAB) in the high microwave frequency region (10–18 GHz) [4–7]. Nevertheless, the 5G technologies signals fall in the low microwave frequency region (2–10 GHz), especially in the C-band (4–8 GHz). Therefore, further expanding the low frequency absorption bandwidth of the microwave absorption materials is critical but remains challenging.
It is anticipated that magnetic materials with superior natural resonance [8] and exchange resonance [9] would be effective in achieving excellent low-frequency microwave absorption, owing to their strong magnetic loss ability. However, it is difficult to further improve the magnetic loss ability of the magnetic materials due to the Snoke’s limit [10]. Geometric regulation, particularly the construction of magnetic anisotropic assemblies, is an efficient strategy for promoting the Snoke’s limit. For example, Che et al. designed the nonsymmetric hammer-shaped Fe/Fe3O4@SiO2 composite, achieving strong magnetic loss ability [11]. The nonsymmetric distribution of the magnetic components is beneficial to enhance the magnetic anisotropy, which further promotes the Snoke’s limit. Moreover, the magnetic anisotropy is also affected by the compositional discrepancy of the magnetic components. Magnetic heterostructures, especially at the nanoscale, have great potential for enhancing the magnetic anisotropy. Wang et al. constructed the ferromagnetic/antiferromagnetic heterostructures, confirming that magnetic pinning effect induced by the interfacial magnetic bias improves the magnetic anisotropy and low frequency permeability [12]. Therefore, achieving the nonsymmetric distribution of the nanoscale magnetic heterostructures could be an effective strategy to promote the Snoke’s limit. Furthermore, the high density of the magnetic materials results in a high filling ratio in the absorbers, which is disadvantageous for their applications. It is also important to combine magnetic materials with a lightweight dielectric material that can simultaneously achieve strong magnetic loss and low density.
Carbon nanocoils (CNCs) have been considered as a kind of versatile nanomaterial in many fields [13–27]. Compared to other carbon materials, CNCs possess unique chiral morphology and excellent dielectric properties, making them promising candidates for microwave absorption. However, the combination of CNCs with magnetic components to form chiral-dielectric-magnetic trinity composites is still in its infancy, and the underlying loss mechanisms remain unclear. In this work, we report a novel multifunctional carbon foam with nanoscale chiral magnetic heterostructures, which exhibits excellent broadband microwave absorption in the low frequency range. The detailed loss mechanisms are investigated through experiments and simulations, providing new insights into the design of high-performance microwave absorbers.
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Hao Zhang, Kaili Kuang, Yifeng Zhang, Chen Sun, Tingkang Yuan, Ruilin Yin, Zeng Fan, Renchao Che, Lujun Pan (2025). Multifunctional Carbon Foam with Nanoscale Chiral Magnetic Heterostructures for Broadband Microwave Absorption in Low Frequency. Nano-Micro Letters. https://doi.org/10.1007/s40820-025-01658-8
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Frequently Asked Questions
What is the main achievement of this study?
The study constructs a novel multifunctional carbon foam with nanoscale chiral magnetic heterostructures, achieving an ultrabroad effective absorption bandwidth (EAB) of 14 GHz and full C-band coverage (4 GHz) in low frequency microwave absorption.
How does the carbon foam achieve broadband microwave absorption?
The 3D porous CNC-carbon foam network provides excellent impedance matching and strong conduction loss, while the FeNi-carbon interfaces induce interfacial polarization loss. Additionally, the nanoscale chiral magnetic heterostructures achieve magnetic pinning and coupling effects, enhancing magnetic anisotropy and magnetic loss capability.
What is the significance of the C-band coverage?
The C-band (4-8 GHz) is crucial for 5G communications. Achieving full C-band coverage with an EAB of 4 GHz means the material can effectively absorb microwaves in this frequency range, addressing the challenge of low-frequency absorption.
What methods were used to confirm the loss mechanisms?
Density functional theory (DFT) calculations confirmed the interfacial polarization loss, while micromagnetic simulations revealed magnetic pinning and coupling effects. Permeability analysis further supported the enhanced magnetic loss capability.
What are the potential applications of this material?
This material can be used in electromagnetic interference shielding, radar absorption, and other applications requiring lightweight and efficient microwave absorption in low frequency bands, particularly for 5G technologies.
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