Strong Dependence of Magnetic Damping and Magnetization on Deposition Temperature in Highly Magnetostrictive NiZnAl Ferrite Thin Films

Abstract

Zn/Al co-doped nickel ferrites (NZAFO) with ultralow magnetic damping and large magnetostriction are critically needed for use in tunable spintronic devices and dissipationless quantum computation. However, the growth of epitaxial NZAFO thin films with optimized properties is difficult due to their tendency to form anti-site defects and antiphase boundaries, even on isostructural spinel substrate. Here, growth temperature-dependent ferromagnetic resonance (FMR) and magnetization have been systematically investigated. The saturate magnetization and damping linewidth have decreased from 114 to 70 emu/cc and 321 to 12 Oe as deposition temperature increased from 500 °C to 650 °C, respectively. With further optimization of the film thickness, a minimum FMR linewidth of 7.5 Oe has been observed, only 1.74% of that of bulk form NZAFO materials. Further increasing of deposition temperature to 700 °C results in a dramatic increase in the magnetic coercive field and damping linewidth. The magnetostriction and magnetocrystalline anisotropy are relatively stable in a large temperature range. The strong dependence between magnetic properties and the deposition temperature has been explained in terms of cation redistribution and evaporation. The insulating ferrimagnetic NZAFO with ultralow microwave loss and strain tunable static and dynamic magnetic properties serve as a promising candidate to be used in various tunable electronic devices.