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Title: Composition Mapping of Co-Pt-Ti-O Perpendicular Magnetic Recording Media by Simultaneous EDS and EELS Spectrum Imaging

Abstract

For nearly a decade core-loss elemental mapping by energy-filtered transmission electron microscopy (EFTEM) with {approx}1 nm resolution has contributed greatly to the understanding of Co(Cr)-based thin-film longitudinal magnetic recording media for computer hard disks. Intergranular layers of non-ferromagnetic Cr-enriched material a few nanometers thick are critical for optimum performance since they decouple the magnetic exchange between grains allowing the magnetization within individual grains to be switched independently, as required for high-density recording of data. Modern perpendicular thin-film recording media, which allow higher recording densities than traditional longitudinal media, have a similar columnar grain structure with nonferromagnetic material separating and decoupling the grains. The present work involves plan-view TEM characterization of back-thinned Co-Pt media (Co/Pt{approx}4) with 6 levels of co-sputtered TiO{sub 2} from 0 to 43 vol%. The layer structure of the media was: polished Al substrate/6 nm seed layers/50 nm soft magnetic underlayer/14 nm Ru underlayer/12 nm Co-Pt-TiO{sub 2}/1 nm C overcoat.

Authors:
 [1];  [2];  [2]
  1. ORNL
  2. Stanford University
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Shared Research Equipment Collaborative Research Center
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
931891
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: Microscopy and Microanalysis 2007, Fort Lauderdale, FL, USA, 20070805, 20070809
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; MAGNETIC DISKS; COBALT; PLATINUM; TITANIUM OXIDES; CHEMICAL COMPOSITION; ENERGY-LOSS SPECTROSCOPY; X-RAY SPECTROSCOPY; TRANSMISSION ELECTRON MICROSCOPY; TEM; Spectrum Imaging; EDS; EELS; Composition Mapping; Recording Media; Thin Film; Co; Pt; TiO2

Citation Formats

Bentley, James, Risner, Juliet D., and Sinclair, Prof. Robert. Composition Mapping of Co-Pt-Ti-O Perpendicular Magnetic Recording Media by Simultaneous EDS and EELS Spectrum Imaging. United States: N. p., 2007. Web.
Bentley, James, Risner, Juliet D., & Sinclair, Prof. Robert. Composition Mapping of Co-Pt-Ti-O Perpendicular Magnetic Recording Media by Simultaneous EDS and EELS Spectrum Imaging. United States.
Bentley, James, Risner, Juliet D., and Sinclair, Prof. Robert. Mon . "Composition Mapping of Co-Pt-Ti-O Perpendicular Magnetic Recording Media by Simultaneous EDS and EELS Spectrum Imaging". United States. doi:.
@article{osti_931891,
title = {Composition Mapping of Co-Pt-Ti-O Perpendicular Magnetic Recording Media by Simultaneous EDS and EELS Spectrum Imaging},
author = {Bentley, James and Risner, Juliet D. and Sinclair, Prof. Robert},
abstractNote = {For nearly a decade core-loss elemental mapping by energy-filtered transmission electron microscopy (EFTEM) with {approx}1 nm resolution has contributed greatly to the understanding of Co(Cr)-based thin-film longitudinal magnetic recording media for computer hard disks. Intergranular layers of non-ferromagnetic Cr-enriched material a few nanometers thick are critical for optimum performance since they decouple the magnetic exchange between grains allowing the magnetization within individual grains to be switched independently, as required for high-density recording of data. Modern perpendicular thin-film recording media, which allow higher recording densities than traditional longitudinal media, have a similar columnar grain structure with nonferromagnetic material separating and decoupling the grains. The present work involves plan-view TEM characterization of back-thinned Co-Pt media (Co/Pt{approx}4) with 6 levels of co-sputtered TiO{sub 2} from 0 to 43 vol%. The layer structure of the media was: polished Al substrate/6 nm seed layers/50 nm soft magnetic underlayer/14 nm Ru underlayer/12 nm Co-Pt-TiO{sub 2}/1 nm C overcoat.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

Conference:
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  • No abstract prepared.
  • A magnetoplumbite type of Ba ferrite (BaM) thin layer was deposited on a 9 nm thick Pt underlayer, and excellent c-axis orientation was observed even for an 8 nm thick BaM layer, which corresponds to only three or four BaM unit cells. The grain size was almost in the same range of 60{endash}85 nm even when the BaM layer thickness t{sub BaM} decreased from 60 to 17 nm, and t{sub BaM} should be reduced below 10 nm to make a grain size smaller than 50 nm. However, the perpendicular coercivity H{sub c{perpendicular}} and squareness S{sub {perpendicular}} decreased drastically from 2.6more » to 0.5 kOe and from 0.6 to 0.2, respectively, with the decrease of t{sub BaM} from 60 to 8 nm because of higher demagnetizing field and susceptibility to thermal fluctuation. On the other hand, the [BaM(5{endash}24nm)/Pt(9nm)]{sub 3} multilayer exhibited higher H{sub c{perpendicular}} and larger S{sub {perpendicular}} than the BaM/Pt bilayer for the same BaM layer thickness and H{sub c{perpendicular}} and S{sub {perpendicular}} of the [BaM(8nm)/Pt(9nm)]{sub 3} multilayer was 2.0 kOe and 0.6, respectively. It was clarified that the deposition of the BaM/Pt multilayer was very effective for achieving a high perpendicular magnetic anisotropy constant even for the ultrathin BaM layer. {copyright} 2001 American Institute of Physics.« less
  • Polarization dependent extended x-ray absorption fine structure (PD-EXAFS) and magnetic circular dichroism (MCD) measurements of CoCrTa and CoCrPt films, sputter deposited at varying substrate temperatures, were performed to investigate the average local structure and chemistry about the Ta, Pt, and Co atoms and the average magnetic moment of the Co and Cr atoms within these films. Results from the MCD measurements indicate the average net magnetic moment of the Cr atoms is opposite in direction and five percent in amplitude relative to the Co moments. Inspection of the Fourier transforms of the XAFS data from these samples shows an increasemore » in structural disorder around the Ta and Pt atoms with increasing substrate deposition temperature. A further comparison between the Ta and Pt edge EXAFS results show that the temperature-dependent increase in structural disorder is greater around the Ta atoms in the CoCrTa system than it is around the Pt atoms in the CoCrPt system. {copyright} {ital 1996 American Institute of Physics.}« less
  • Perpendicular magnetic media are expected to replace longitudinal hard-disk media in the near future, and to provide continued increases in areal density beyond the current maximum capacity of longitudinal media. High-resolution analytical electron microscopy is required for the study of these novel thin films because they comprise nanoscale grains and grain boundaries (often {approx}8 nm and {approx} 1 nm, respectively), and because the importance of examining the elemental distribution at near atomic level is paramount to understanding the magnetic performance. While perpendicular media offer many advantages, quantum-mechanical exchange coupling between grains is still problematic and requires the separation of grainsmore » similar to that required in longitudinal media. Energy-filtered TEM (EFTEM) imaging, which was used to examine compositional grain separation in longitudinal media, is capable of generating maps of the elemental distribution within the grains and the boundaries thereby depicting the extent of compositional separation. Combining EFTEM with other microanalytical techniques, such as high resolution TEM with energy-dispersive X-ray spectrometry, allows for both corroboration and easy quantification of individual grain and grain boundary areas. For this analytical TEM study, grain separation was attempted by generating non-magnetic oxygen-rich boundaries, either by flowing O{sub 2} gas during deposition or by sputtering a stable oxide into the magnetic film. These CoPt-O and CoPt-oxide films were DC-magnetron sputtered at room temperature with increasing reactive O{sub 2} or oxide content. Magnetic properties were measured using a magneto-optical polar Kerr magnetometer. Both reactive O{sub 2} and oxide deposition methods, individually, increase grain separation and reduce intergranular exchange coupling, as shown by the hysteresis loop trends in Figures 1a and 2a. The difference between coercivity (Hc) and nucleation field (Hn) is a measure of the extent of exchange decoupling. The large increase in this loop shearing parameter as O{sub 2} or oxide content is increased is clear evidence of a corresponding decrease in exchange coupling.« less