Functional magnetic thin films

Functional magnetic films are used in a wide range of applications, from computer hard drives to micro-magnetic sensors. By controlling the film growth and composition, the functional properties can be tuned for the application. The majority of the films investigated are fabricated using DC/RF sputtering on one of the four systems at Sheffield. Each system is unique and provides different capabilities for the thin film growth. This includes 3- or 6-gun sputtering, and co-sputtering-evaporation. By changing the growth pressure, and sputtering power the film growth rate is changed, and this controls the film growth on the substrate. This allows for amorphous to polycrystalline films to be grown for the same composition and thickness, allowing for the functional properties to be studied for the different morphologies.

A range of functional films has been studied in the group. This includes magnetostrictive films, which have applications such as field and strain sensors. The films studied include FeCo-X, where X has been Al and Cr to help increase the magnetostriction constant within the films, and FeGa, which was fabricated in the co-sputter-evaporation system, and has also been investigated as an amorphous film with the addition of Si and B. Soft magnetic thin films have been studied to determine how changing the composition changes the soft magnetic properties; this involves using either the 3- or 6-gun sputter systems, to control the composition of the different elements within the films. 

Further thin film work has used underlayers and multilayers to control and change the magnetic properties of the films, including creating films with out of plane magnetisation, by creating multilayers containing ultra thin Co and Ni layers.