Thin Hf layers in Nb studied by the perturbed angular correlation method. I. Characterization of thin layers in Nb-Hf-Nb layered structures

Nb-Hf-Nb sandwich samples were prepared by electron-gun evaporation. The thickness of the Hf layers ranged from 1 to 200 nm. The structural properties were studied with use of the perturbed angular correlation method. The measurements show that the Hf layers with thicknesses larger than 20 nm are oriented with the c axis of the hcp structure parallel to the surface normal. If the thickness of the Hf layer is smaller than 20 nm, the layer is strongly disturbed