[en] In this work the perturbed angular correlation technique is used to locally monitor the epitaxy and thermal stability of the hafnium layer in a Zr/Hf/Zr multilayer. The studies reveal that the system is highly homogeneous and presents high epitaxy. Measurements at high temperatures show that no HfO_x formation occurs up to 562 K but at this temperature the Hf layer is no longer oxygen-defect free.

[en] The hyperfine field at ¹⁸¹Ta lattice sites in nanostructured HfO₂ thin films was studied by the Perturbed Angular Correlation (PAC) technique. Thin oxide films were deposited by Electron Beam Evaporation on a silicon substrate. The thickness of the films was ∼100 nm and ∼250 nm. Radioactive ¹⁸¹Hf nuclei were produced by neutron activation of the film samples in the Brazilian Research Reactor (IPEN IEA-R1) by the reaction ¹⁸⁰Hf(n,γ)¹⁸¹Hf. PAC measurements were carried out after annealing at 1473 K. The PAC technique allows the determination of the electric field gradient (EFG) at the probe sites.