Villari magnetomechanical coupling at hcp-Cobalt thin films on flexible substrates

[Display omitted] •Innovative approach on VSM measurements with stress application.•Magnetron sputtered magnetic thin films fabrication.•Growth of Cobalt thin films on flexible substrate.•Growth of buffer-layered Cobalt films to optimize structural properties.•Villari magnetomechanical effect in Cobalt flexible thin films. In this article, the structural and magnetic behavior of Cobalt (Co) thin films deposited on flexible Kapton substrates by means of magnetron sputtering technique at ambient temperature are investigated. In order to reveal the impact of Co structure, the case of as-deposited and buffer-layered Co films are studied. The structural characterization was carried out by X-ray diffraction showing the HCP structure of Co. Scanning electron microscopy was conducted to reveal the morphological characteristics of the samples. The magnetic characterization has been performed by means of vibrating sample magnetometry at ambient conditions. Both systems of Co films were subjected in a wide range of applied strains using a newly constructed sample holder in order to investigate the Villari effect. Upon the progressive increase of strain, the magnetization of Co films exhibits a non-monotonic behavior with a local maximum between 2 and 3%. This non-monotonic behavior of magnetization is ascribed to the possible interplay of two main mechanisms. The first mechanism relies on the change of the interatomic distances in the crystal structure at relatively low values of the experienced strain by Co films. The second mechanism is based on the microstructural modification of Co grains as strain exceeds a certain value.