Study of influence of underlayer on the properties of magnetron sputtered samarium cobalt thin films

This paper presents the results of the investigation on the deposition and characterization of samarium cobalt (SmCo) thin films. To understand the underlayer effects on the magnetic properties, SmCo thin films were deposited onto Cr/SiO2/Si, Cr/Si and Si at 600 °C and an operating argon pressure of 1.3 Pa using a direct current unbalanced magnetron sputtering technique. These films were characterized for composition, structure, microstructure and magnetic properties using Rutherford Backscattering Spectrometry, X-ray Diffractometer, Atomic Force Microscope and Superconducting Quantum Interference Device, respectively. The films deposited on the three substrate/intermediate layer combinations have the same atomic composition of SmCo5.51O0.4. All prepared films are crystalline with predominantly hexagonal Sm2Co17 phase having grains of different orientations. The films deposited directly onto a Si substrate show relatively poor crystallinity and have a larger tensile residual stress in the film plane than those deposited with a Cr underlayer. The films prepared with a Cr underlayer are relatively dense with smaller grain sizes than those deposited directly onto a Si substrate. The in-plane hysteresis loops measured at room temperature indicate that the films deposited onto a Cr underlayer have relatively better magnetic properties. The use of a SiO2 film as a barrier layer between Cr and Si decreases the intrinsic coercivity of the film by about 6.3% when compared with the film without a SiO2 layer.