Exploring the role of oxygen vacancies on the magnetic and electromagneticabsorption properties of La 3+ -modified M-Type hexaferrite with Al 3+ doping.

The demand for effective microwave-absorbing materials has recently surged due to rapid advancements in electromagnetic 
devices. Recently, engineering oxygen vacancies has also become one of the effective ways to develop efficient microwave-
absorbing materials. So, understanding the electromagnetic absorption mechanism of these materials has become crucial for 
better engineering of such materials. This article investigates the magnetic properties along with the electromagnetic 
absorption mechanism of M-type hexaferrite, with optimal incorporation of rare-earth element La 3+ and dopping of 
transition metal Al 3+ . The presence of La 3+ ions at an optimal level promotes the reduction of Fe 3+ to
Fe 2+ cations create oxygen vacancies to offset the electrical charge imbalance. This phenomenon impacts both the 
magnetic and electromagnetic characteristics of the materials. The presence of Fe 2+ cations enhanced the spin-orbital 
interaction, resulting in the strong magnetic anisotropy field along the c-axis. The lowest reflection loss (RL) of -36.37 dB at 
14.19 GHz, is observed with a bandwidth of 3.61 GHz below -10 dB for x = 0.6. These microwave absorption properties can be 
attributed to the mutual compensation between dielectric and magnetic losses, which arise from phenomena like dielectric 
relaxation, magnetic resonance, and conduction loss due to electron hopping between Fe 3+ and Fe 2+ , with proper 
incorporation of the attenuating constant and excellent impedance matching, along with microstructure of the materials.
Furthermore, the material's exceptional absorption properties are also influenced by the rapid movement of oxygen vacancies
from its interior to its surface when exposed to high frequencies, thereby impacting its conductivity. Therefore, it is 
believed that the regulation of oxygen vacancies can serve as a versatile strategy for developing materials with efficient 
microwave-absorbing capabilities.