Influence of structure and cation distribution on magnetic anisotropy and damping in Zn/Al doped nickel ferrites

An in-depth analysis of Zn/Al doped nickel ferrite thin films grown by reactive magnetron sputtering was conducted to gain insight into the magnetic properties interesting for applications in spintronics. The material is insulating, ferromagnetic at room temperature and has a low magnetic damping with additional strong magnetoelastic coupling. The sample system is analyzed with regard to crystal structure, chemical composition and static as well as dynamic magnetic properties. Thus a correlation between composition, strain, cation distribution, magnetocrystalline anisotropy and damping is evidenced. X-ray magnetic circular dichroism spectra and field dependent curves at the L3;2 edges of Ni and Fe are performed to complement integral magnetometry measurements and identify their magnetic contributions to the hysteresis. In particular, a strong in uence of the lattice site occupation of Ni2+ Td and cation coordination of Fe2+ Oh on the intrinsic damping is found. Furthermore, the vital role of the incorporation of Zn2+ and Al3+ is evidenced by comparison with a sample of altered composition. A strain-independent reduction of the magnetic anisotropy and damping by adapting the cation distribution is demonstrated.