Laser ablation deposition has been used to synthesize nanoscale ferrite structures. Our investigations were performed on NiZn and Zn ferrite films deposited on silicon(100) substrates. Films produced by laser ablation at room temperature were annealed at 550°C for 1h. Other films were deposited directly at a 550°C substrate temperature without subsequent annealing. Complementary x-ray diffraction and superconducting quantum interference device magnetometry measurements helped identify the optimum laser ablation deposition conditions for obtaining the desired nanoferrite structures. From the hysteresis loops at 300 and 10K we identified the paramagnetic or ferromagnetic behavior of the films. The zero field cooled–field cooled (ZFC–FC) magnetization, M(T), curves yielded the value of the blocking temperature in both NiZn and Zn ferrite systems.

We measured the change in the average hyperfine field strength of several high entropy alloys in relation to small compositional deviations from the equiatomic alloy, FeCoNiCuMn. Mössbauer spectra of four psuedo-binary systems, in which Mn content is increased and another element was decreased in equal measure, reveal several discrete peaks in the hyperfine field distribution that show evidence of the discrete exchange interactions between magnetic elements in the alloy. A simple linear regression modelling the perturbation of the average hyperfine field when the composition is altered calculates the contribution of each atom to the overall average. The average hyperfine field is linear with T_c, so these values allow us to estimate T_c for alloys with more complex compositional variation within the window of linearity (<24% Mn based on other alloys). The results were confirmed experimentally by calculating T_c of two new alloys, Fe₁₉Co₂₀Ni₁₉Cu₁₉Mn₂₃ and Fe₁₉Co₂₀Ni₁₉Cu₂₀Mn₂₂.