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Title: Quantitative transmission electron microscopy analysis of multi-variant grains in present L1{sub 0}-FePt based heat assisted magnetic recording media

We present a study on atomic ordering within individual grains in granular L1{sub 0}-FePt thin films using transmission electron microscopy techniques. The film, used as a medium for heat assisted magnetic recording, consists of a single layer of FePt grains separated by non-magnetic grain boundaries and is grown on an MgO underlayer. Using convergent-beam techniques, diffraction patterns of individual grains are obtained for a large number of crystallites. The study found that although the majority of grains are ordered in the perpendicular direction, more than 15% of them are multi-variant, or of in-plane c-axis orientation, or disordered fcc. It was also found that these multi-variant and in-plane grains have always grown across MgO grain boundaries separating two or more MgO grains of the underlayer. The in-plane ordered portion within a multi-variant L1{sub 0}-FePt grain always lacks atomic coherence with the MgO directly underneath it, whereas, the perpendicularly ordered portion is always coherent with the underlying MgO grain. Since the existence of multi-variant and in-plane ordered grains are severely detrimental to high density data storage capability, the understanding of their formation mechanism obtained here should make a significant impact on the future development of hard disk drive technology.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [1] ;  [2] ;  [4] ;  [2] ;  [1] ;  [2] ;  [4] ;  [4] ;  [2]
  1. Data Storage Systems Center, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)
  2. (United States)
  3. SYSU-CMU Joint Institute of Engineering, Sun Yat-Sen University, Guangzhou (China)
  4. (China)
  5. Department of Materials Science and Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)
Publication Date:
OSTI Identifier:
22402659
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 19; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; DENSITY; DIFFRACTION; FCC LATTICES; GRAIN BOUNDARIES; HEAT; MAGNESIUM OXIDES; MAGNETIC DISKS; ORIENTATION; THIN FILMS; TRANSMISSION ELECTRON MICROSCOPY