Alison Cowan

Alison joined the CDT in September 2015 having previously completed a Masters in Physics at Queen's University Belfast.

CDT PhD Project:

Exploring the Role of Magnetostriction in Permalloy Multilayers using Transmission Electron Microscopy

Supervisors:

Professor Stephen McVitie, University of Glasgow

Professor Robert Bowman, Queen's University Belfast

As the size of storage devices decreases into the nano-scale, a material with a low magnetostriction is sought after as shielding in magnetic recording heads. There are a number of ways in which magnetostriction can be analysed, but most importantly, a nano-scale visualisation of the magnetic structure can prove invaluable when in conjunction with other measurement techniques.

A permalloy of composition 80/20 nickel and iron is one of the most studied materials in magnetism. However, a slight variation in the composition and thickness can have a large effect on the magnetostriction value leading to an overall consequence in the device application. In this project we aim to identify the subtle effects magnetostriction has on continuous and patterned multilayers of permalloy with various configurations.

The facilities at Glasgow are ideal for investigating magnetism due to its advanced Lorentz TEM, allowing characterisation of the magnetic orientation of the sample to be investigated at the nano-scale. In-situ imaging will allow field and temperature driven behaviour to be performed. Furthermore, aberration corrected STEM imaging can be used on the planar and cross-sectional films to probe the physical and compositional structures below the nano-metre length scale. The full characterisation of materials will allow optimisation of recording head materials containing permalloy multilayers.

Micro magnetic simulations can also be performed to assist the interpretation of experimental data. The combination of expertise at Queen’s and Glasgow will be used to interpret and optimise the best materials properties for device applications.