FePt based advanced magnetic recording media

Loading...

View/Download File

Wang_umn_0130E_13520.pdf (6.32 MB)

Persistent link to this item

https://hdl.handle.net/11299/147273

Statistics

View Statistics

Journal Title

Journal ISSN

Volume Title

Title

FePt based advanced magnetic recording media

Authors

Wang, Hao

Published Date

2013-02

Publisher

Type

Thesis or Dissertation

Abstract

In future extremely high density magnetic recording, FePt is considered as a promising candidate for future recording media materials. In this thesis work, FePt media with composite structure have been systematically studied in the forms of both granular media and bit patterned media (BPM). Continuous FePt films with surface roughness of less than 0.3 nm are achieved in FePt hard magnetic films, exchanged coupled composite (ECC) films and graded films. Nanoimpriting and block-copolymer lithography are employed to fabricate BPM. The switching field distribution (SFD) broadening and degradation of FePt BPM are studied. The reduction of SFD has been achieved using a post-annealing process. Both ECC and graded FePt BPM with sub-30 nm dot size have been experimentally demonstrated on large substrates for the first time. It is confirmed that the patterned graded BPM sample has smaller switching field and larger thermal energy barrier than the ECC sample does. Ultra-thin FePt granular media with graded composition was directly fabricated using a spontaneous layer diffusion process between the FePt and Pt layers during film deposition. A large gain factor of 3.74 was found in this spontaneously formed FePt graded granular media. A nanopatterning process, named as the Embedded Mask Patterning (EMP), is proposed and experimentally demonstrated based on the FePt magnetic recording media. In this process the granular structure is defined by a sputtering-deposited mask layer, while the magnetic properties are determined by the FePt continuous film. Grain size can be decreased by optimizing the mask layer only. A non-ideal surface anisotropy effect has been observed on the magnetization reversal process of both L10 phase FePt nanoparticles, and (001) textured L10 FePt thin film with island structure. The broken symmetry of the surface creates surface anisotropy and also weakens the exchange coupling. The elimination of the surface effect has been experimentally demonstrated by epitaxially capping a Pt layer on FePt. After being embedded in a Pt matrix, the exchange coupling between the surface portion and internal portion of FePt islands was enhanced.

Keywords

FePt

Granular media

Heat assisted magnetic recording

Magnetic recording

Patterned media

Thin film

Description

University of Minnesota Ph.D. dissertation. February 2013. Major: Electrical Engineering. Advisor: Professor Jian-Ping Wang. 1 computer file (PDF); xvi, 166 pages.

Related to

Replaces

License

Collections

Dissertations

Series/Report Number

Funding information

Isbn identifier

Doi identifier

Previously Published Citation

Suggested citation

Wang, Hao. (2013). FePt based advanced magnetic recording media. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/147273.

Content distributed via the University Digital Conservancy may be subject to additional license and use restrictions applied by the depositor. By using these files, users agree to the Terms of Use. Materials in the UDC may contain content that is disturbing and/or harmful. For more information, please see our statement on harmful content in digital repositories.