## 1 Introduction  
In recent decades, advanced electromagnetic (EM) applications have taken on a fundamental role in areas such as satellite communication, radar systems, and wireless networks [1; 2; 3; 4; 5]. However, the problem of powerful electromagnetic interference (EMI) is becoming serious. EMI pollution certainly hinders the extensive utilization of electromagnetic wave (EMW) devices and has many negative effects on the environment and human health. Many efforts have been devoted to investigating efficient solutions for eliminating EMI pollution. Microwave absorption materials (MAMs) are a kind of functional material that can effectively absorb the energy of EMW on their surface and then transform that EMW energy into thermal energy [6; 7; 8; 9]. The development of efficient MAMs is being pursued with high demand, and a considerable number of concepts have been actively investigated in order to develop MAMs with properties including light weight, low price, low thickness, wide absorption bandwidth capability, strong absorption intensity, and anti-oxidation [10; 11; 12].  
Traditional MAMs, including ferrite [13], inorganic metal salts [14], carbonyl iron [15], graphene [16], and conducting polymers [17], have been widely employed in various applications.  
However, these materials are hardly able to satisfy all of the requirements of qualified MAMs. Typically, permittivity (dielectric property) and permeability (magnetic property) are the key factors influence the absorption property of MAMs. Much research has focused on the synthesis and complementation of different components in order to avoid poor impedance matching [18; 19]. According to the EMW absorption mechanism, the microwaves can be absorbed on a large scale and dissipated into thermal energy through magnetic losses and dielectric losses if the characteristic impedance of the absorber is well matched [20]. The composition of magnetic and dielectric materials is significant in improving the impedance matching between permeability and permittivity. Additionally, the employment of different micro-structures in the absorbers could influence their properties. Among the many existing micro-structures, core-shell structures, designed with magnetic components and dielectric components, have attracted a great deal of attention due to their superior microwave absorption properties, which benefit from induced interfacial polarization, as well as improved impedance matching [21].  
One-dimensional (1D) zinc oxide (ZnO)-related nanomaterials have attracted enormous attention in recent decades as dielectric absorbents because of their light weight and dielectric semiconductive properties [22]. To date, many types of ZnO-based materials have been reported that confirm that the absorption property can be modified by compositing ZnO with magnetic materials [22; 23; 24]. Additionally, employing ordinary magnetic-dielectric materials as surrogates for rare metals is cost-effective and utilitarian. Considering the composite synthetic technique of ZnO, many progressive methods have been reported in previous works, such as Zn/ZnO [25], Cu/ZnO [25], and reduced graphene oxide/ZnO [26].  
Previous studies have confirmed that good EM impedance matching and the efficient complementarity between relative permittivity and permeability can be realized by the synergistic effect of the magnetic and the dielectric compositions. In the present work, taking this principle into consideration, we chose ferroferric oxide as the magnetic counterpart and synthesized Fe\({}_{3}\)O\({}_{4}\)/ZnO core-shell structured nanocomposites with Fe\({}_{3}\)O\({}_{4}\) cores and ZnO shells. The morphologies and EMW absorption properties were investigated in detail. This work provides a lead for designing dielectric-magnetic absorbers via a facile method. Moreover, the as-synthesized Fe\({}_{3}\)O\({}_{4}\)/ZnO core-shell structured nanocomposites exhibited an enhanced absorption property, which may be expected to be useful in building a novel platform in advanced EMW absorbers.