Materials for Magnetic Media Using Pulsed Plasmas: Issues, Challenges and Avenues
Rajdeep Singh Rawat1*
1Natural Sciences and Science Education, National Institute of Education, Nanyang Technological University, Singapore
* presenting author:Rajdeep Singh Rawat, email:rajdeep.rawat@nie.edu.sg
This invited presentation will provide the details pulsed plasmas (in pulsed laser ablation facility and plasma focus device) based synthesis and processing of magnetic materials and carbon overcoat in Laser Technology Lab and Plasma Radiation Source Lab of NIE/NTU, Singapore. Equiatomic iron-platinum (FePt) and cobalt-platinum (CoPt) alloy films with an L10-ordered structure are prime candidate materials for ultra-high density magnetic recording media. Nanostructured hard magnetic materials are attractive for ultra-high density magnetic recording media whereas carbon overcoat are required for magnetic media protection. As-grown FePt/CoPt films, grown using different plasma assisted methods, are generally in magnetically soft A1 phase and have to be transformed to magnetically hard L10 phase by high temperature post-deposition annealing. The high temperature annealing however leads to undesirable grain growth and increased exchange coupling effects. Various schemes have been implemented by us to reduce the phase transition temperature such as magnetic trapping, composites of magnetic material in non-magnetic matrix and use of ion irradiation by plasma focus device. Issues related to impurity phase formation in PLD based FePt thin film synthesis and corresponding solutions will also be discussed. The synthesis of magnetically very hard nanostructured CoPt thin films using plasma focus device will also be discussed in details with the novelty of extremely high synthesis rate and no impurity phase formations. The use of pulsed high energy density pulsed plasmas from plasma focus device will be discussed for ultrafast synthesis of carbon overcoat with high sp3 content will also be presented with only marginal effect on magnetic properties of underneath magnetic media.


Keywords: Magnetic nanoparticles, pulsed energetic plasmas, energetic ion irradiations, phase transition, carbon overcoat