In situ dynamics response mechanism of the tunable length-diameter ratio nanochains for excellent microwave absorber

Faster response benefits the high-performance of magnetic material in various live applications. Hence, enhancing response speed toward the applied field via engineering advantages in structures is highly desired. In this paper, the precise synthesis of Co nanochain with the tunable length-diameter ratio is realized via a magnetic-field-guided assembly approach. The Co nanochain exhibits enhanced microwave absorption performance (near to -60 dB, layer thickness 2.2 mm) and broader effective absorption bandwidth (over 2/3 of total S, C, X, Ku bands). Furthermore, the simulated dynamic magnetic response reveals that the domain motion in 1D chain is faster than that in 0D nanoparticle, which is the determining factor of magnetic loss upgrade. Meanwhile, based on the controllable magnetic field experiment via in situ transmission electron microscopy, the association between magnetic response and microstructure is first present at the nanometer-level. The real and imaginary parts of relative complex permeability are determined by the domain migration confined inside Co nanochain and the magnetic flux field surrounded outside Co nanochain, respectively. Importantly, these findings can be extended to the novel design of microwave absorbers and promising candidates of magnetic carriers based on 1D structure.