The Effect of ZnO(002) on the Magnetic, Electrical, and Adhesive Characteristics of FePdB/ZnO/FePdB Thin Films

Abstract

A multilayered FePdB(X Å)/ZnO(500 Å)/FePdB(X Å) film (X is 25, 50, 75, and 100 Å) was sputtered onto a glass substrate at room temperature (RT). X-ray diffraction (XRD) measurements revealed main peaks of highly crystalline ZnO(002) and FePd(200). Minor crystalline peaks, namely, those for ZnO(004), FePd(111), and FePd(002), were also detected. As the FePdB thickness increased, the crystallinity of ZnO(002) and FePd(200) increased. Strong peak for FePd(200) induced magnetocrystalline anisotropy due to the crystallinity of ZnO(002). This increased the low-frequency alternating-current magnetic susceptibility (Χac) and decreased the electrical resistivity (ρ) of the film. Thus, the Χac value increased with the FePdB thickness because of magnetocrystalline anisotropy. The highest value of Χac was 1.9, which was obtained at a FePdB thickness of 100 Å and at the highest spin sensitivity at an optimal resonance frequency of 30 Hz. ρ decreased as the FePdB thickness increased probably because of electron scattering at the grain boundaries or impurities within the material. ρ ranged from 1650 to 720 μΩ cm. The FePdB(100 Å)/ZnO(500 Å)/FePdB(100 Å) sample had the maximum Χac of 1.9 and a low ρ (720 μΩ cm) and is therefore suitable for magnetic and electrical applications. In addition, the surface energy is related to the adhesion of the film; a high surface energy corresponds to strong adhesion. The surface energy decreased with increasing degree of FePdB crystallization and increasing FePdB thickness, resulting in weaker adhesion.