Fabrication and characterisation of L10 ordered FePt thin films and bit patterned media

Abstract

Highly ordered magnetic materials with high perpendicular magnetic anisotropy (PMA),such as the L10 ordered FePt, and new recording technologies, such as bit patternedmedia (BPM), have been proposed as solutions to the media trilemma problem andprovide promising strategies towards future high-density magnetic data storage media.L10 ordered FePt thin films can provide the necessary high PMA. However, the orderingof this material perpendicular to the plane of the films remains challenging sincehigh-temperature and time-consuming processes are required.In this work, a remote plasma sputtering system has been used for the investigationof FePt thin films in order to understand if the greater control of process parametersoffered by this system can lead to enhanced ordering in L10 FePt thin films at lowtemperatures compared with conventional dc magnetron approaches. More specifically,the effect of the different substrate temperatures and the target bias voltages onthe ordering, the microstructure and the magnetic properties of FePt thin films wasinvestigated.Highly ordered FePt thin films were successfully fabricated after post-annealingprocesses and were patterned into arrays of FePt islands. This patterning process wascarried out with e-beam lithography and ion milling. Initial MFM measurements ofthese islands showed their single-domain structure for all the island sizes, which indicatedthe high PMA of the FePt.Magnetometry measurements were also carried out with a novel polar magnetoopticalKerr effect (MOKE) system which was designed and built during this project.This system has unique capabilities which are a) the application of uniform magneticfield up to 2 Tesla, b) the rotation of the field to an arbitrary angle and c) the use oflasers of four different wavelengths. The combination of these abilities enabled measurementson ordered FePt thin films and patterned media which can pave the way forfurther highly sensitive measurements on magnetic thin films and nanostructures.

Date of Award	31 Dec 2016
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Paul Nutter (Supervisor) & Thomas Thomson (Supervisor)