Very High Coercivity Chemically Deposited Co–Ni Films

1965 ◽  
Vol 36 (3) ◽  
pp. 948-949 ◽  
Author(s):  
J. S. Judge ◽  
J. R. Morrison ◽  
D. E. Speliotis
Keyword(s):  
High Coercivity ◽  
Very High

Llo Phase Formation in CoPt Thin Films

1997 ◽  
Vol 475 ◽  
Author(s):  
R. A. Ristau ◽  
K. Barmak ◽  
K. R. Coffey ◽  
J. K. Howard
Keyword(s):  
Thin Films ◽  
Phase Formation ◽  
Volume Fraction ◽  
Parent Phase ◽  
High Volume ◽  
Nucleation And Growth ◽  
High Coercivity ◽  
Nucleation And Growth Mechanism ◽  
Very High ◽  
Disorder Transition Temperature

ABSTRACTThe high magnetic anisotropy and high coercivity of equiatomic CoPt thin films make them attractive as potential materials for magnetic recording applications. Magnetic coercivity (Hc) over 10 kOe has been measured in films in which the as-deposited fee phase has been partially transformed to the atomically ordered Ll0 phase. Very high Hc has been related to high volume fraction and small size of the Ll0 precipitates. A better understanding of the Ll0 phase formation and quantification of volume fraction is critical to optimizing the magnetic properties of this material.As we have previously reported, an increase in Hc was observed with an increase in Ll0 volume fraction in 10 nm thick, equiatomic CoPt films. In our current investigation we have observed that, at anneal temperatures far from the order/disorder transition temperature, e.g. at T = 0.6 Tc, numerous, very fine Ll0 precipitates are seen, some of which cluster at the parent phase grain boundaries. At T = 0.85 Tc, very few, larger Ll0 regions were seen. As precipitates of the ordered phase grow to impingement, antiphase boundaries (APB) are formed. This is consistent with a heterogeneous nucleation and growth mechanism for the formation of the Ll0 phase throughout the temperature range studies.

Magnetometry and recording on very high coercivity cobalt alloy disk media

1991 ◽  
Vol 27 (6) ◽  
pp. 5034-5036
Author(s):  
T. Coughlin ◽  
N. Viswanathan ◽  
D. Speliotis
Keyword(s):  
High Coercivity ◽  
Cobalt Alloy ◽  
Very High ◽  
Alloy Disk

scholarly journals HIGH DENSITY RECORDING ON BARIUM FERRITE AND VERY HIGH COERCIVITY THIN FILM RIGID DISKS

1991 ◽  
Vol 15 (S_2_PMRC_91) ◽  
pp. S2_51-56 ◽  
Author(s):  
Dennis SPELIOTIS ◽  
William LYNCH ◽  
Joseph BURBAGE ◽  
Rick KBIRSTEAD
Keyword(s):  
Thin Film ◽  
Barium Ferrite ◽  
High Density ◽  
High Coercivity ◽  
Rigid Disks ◽  
High Density Recording ◽  
Very High

Investigation of copt and copt + ZrOx thin films for magnetic storage media using high-resolution analytical electron microscopy

1996 ◽  
Vol 54 ◽  
pp. 578-579
Author(s):  
R. A. Ristau ◽  
K. Barmak
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Grain Size ◽  
Signal To Noise Ratio ◽  
High Coercivity ◽  
Magnetic Storage ◽  
Signal To Noise ◽  
Storage Media ◽  
Magnetic Storage Media ◽  
Very High

Materials for very high density magnetic storage media, with capacities of 10 Gbits/in2 and beyond, require high coercivity and high signal to noise ratio. To achieve storage densities of this level engineering of the material to produce very fine, magnetically decoupled domains is necessary. We have characterized the microstructure and microchemistry of 10 nm thick CoPt and CoPt + ZrOx thin films, as deposited and annealed, using transmission electron microscopy (TEM) and nanometer-scale energy dispersive x-ray spectroscopy (EDS).CoPt has a very high coercivity (Hc) when annealed to produce the ordered Ll0 phase. Annealing also increases grain size which reduces the signal to noise ratio. Co-sputtering CoPt with ZrOx was intended to reduce grain size. TEM micrographs in Figure 1 show that grain growth was dramatically reduced in the CoPt + ZrOx films. Essential to the development of optimum material properties are quantified grain size measurements, yet owing to the small grain size and the complexity of TEM images due to diffraction contrast there are few systematic studies of grain size in thin films.

Formation of submicron-sized SrFe12−xAlxO19 with very high coercivity

2008 ◽  
Vol 320 (6) ◽  
pp. 1068-1072 ◽  
Author(s):  
P.E. Kazin ◽  
L.A. Trusov ◽  
D.D. Zaitsev ◽  
Yu.D. Tretyakov ◽  
M. Jansen
Keyword(s):  
High Coercivity ◽  
Very High

Material Transfer From Media to Head in Heat Assisted Magnetic Recording (HAMR)

2021 ◽  
Author(s):  
Shaomin Xiong ◽  
Robert Smith ◽  
Qing Dai ◽  
Erhard Schreck
Keyword(s):  
Magnetic Recording ◽  
Thermal Gradient ◽  
High Coercivity ◽  
Magnetic Head ◽  
Material Transfer ◽  
Heat Assisted Magnetic Recording ◽  
Disk Interface ◽  
The Media ◽  
Change Material ◽  
Very High

Abstract Heat assisted magnetic recording (HAMR) is one of the leading technologies for next generation magnetic recording. Laser heating is utilized in HAMR to achieve magnetic writing of the very high coercivity media. However, the high temperature environment creates several reliability challenges for the head disk interface (HDI). Material transfer within the HDI under HAMR conditions or emulated HAMR conditions has been studied by experiments and simulations. It is found that the material transfer is mainly driven by thermal gradient and mechanical interaction such as head disk contact. In this paper, we designed an experiment to investigate the material transfer from HAMR media to a flying magnetic head. It shows that thermal gradient, more specifically a hotter media and cooler head, is the driving force for the material accumulation on the head. Furthermore, we calibrated the media temperature by a phase change material to identify the critical temperature that triggers the material transfer process. This study is important to understand the smear formation mechanism in HAMR drives.

Magnetic reversal study of Au-FePt thin films with very high coercivity

2005 ◽  
Vol 41 (10) ◽  
pp. 3346-3348 ◽  
Author(s):  
F.T. Yuan ◽  
S.K. Chen ◽  
L. Horng ◽  
J.L. Tsai
Keyword(s):  
Thin Films ◽  
High Coercivity ◽  
Magnetic Reversal ◽  
Very High ◽  
Fept Thin Films

Very High Resolution Analysis of the Dynamics of a Coronal Plasmoid

1994 ◽  
Vol 144 ◽  
pp. 593-596
Author(s):  
O. Bouchard ◽  
S. Koutchmy ◽  
L. November ◽  
J.-C. Vial ◽  
J. B. Zirker
Keyword(s):  
High Resolution ◽  
Solar Eclipse ◽  
Total Solar Eclipse ◽  
Field Of View ◽  
Small Field ◽  
High Resolution Analysis ◽  
Ccd Observations ◽  
Resolution Analysis ◽  
Very High ◽  
Small Field Of View

AbstractWe present the results of the analysis of a movie taken over a small field of view in the intermediate corona at a spatial resolution of 0.5“, a temporal resolution of 1 s and a spectral passband of 7 nm. These CCD observations were made at the prime focus of the 3.6 m aperture CFHT telescope during the 1991 total solar eclipse.

Monte Carlo Algorithms for Moments of Transition Arrays

1988 ◽  
Vol 102 ◽  
pp. 79-81
Author(s):  
A. Goldberg ◽  
S.D. Bloom
Keyword(s):  
Monte Carlo ◽  
State Vector ◽  
Basis Vector ◽  
Collective State ◽  
Dispersion Characteristics ◽  
Dipole Strength ◽  
The Third ◽  
Monte Carlo Algorithms ◽  
Third Moment ◽  
Very High

AbstractClosed expressions for the first, second, and (in some cases) the third moment of atomic transition arrays now exist. Recently a method has been developed for getting to very high moments (up to the 12th and beyond) in cases where a “collective” state-vector (i.e. a state-vector containing the entire electric dipole strength) can be created from each eigenstate in the parent configuration. Both of these approaches give exact results. Herein we describe astatistical(or Monte Carlo) approach which requires onlyonerepresentative state-vector |RV> for the entire parent manifold to get estimates of transition moments of high order. The representation is achieved through the random amplitudes associated with each basis vector making up |RV>. This also gives rise to the dispersion characterizing the method, which has been applied to a system (in the M shell) with≈250,000 lines where we have calculated up to the 5th moment. It turns out that the dispersion in the moments decreases with the size of the manifold, making its application to very big systems statistically advantageous. A discussion of the method and these dispersion characteristics will be presented.

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