Separated reversal of spins in two spin sublattices and strong microwave absorption with adjustable broad bandwidth in SrFe10.4Zn0.8Sn0.8O19

The dynamical spin resonance stores a large amount of electromagnetic energy. Usually, it is a collective response of all exchange coupled spins. We observed two distinct spin resonances due to two spin sublattices in SrFe10.4Zn0.8Sn0.8O19 sintered at 1300 °C for 6 h. The magnetocrystalline anisotropy ratio of the two spin sublattices is 2. Other SrFe10.4Zn0.8Sn0.8O19 sintered for longer or shorter than 6 h have consecutive resonances. Their antiferromagnetic interaction in the sublattices helps the spins rotate coherently. The separated spin resonances store more magnetic energy than the consecutive one. The sample sintered for 6 h has the highest absorption coefficient, and the absorption bandwidth (RL≤−10 dB) is ≥ 8.35 GHz above 9.65 GHz at a thin thickness of 1.6 mm. As SrFe10.4Zn0.8Sn0.8O19 is sintered at 1400 °C, the microwave absorption is adjusted to be broader than 13.5 GHz from 4.5 to 18+ GHz, covering the C-, X-, and Ku-bands, making SrFe10.4Zn0.8Sn0.8O19 sintered at both conditions very attractive microwave absorbing materials.