High Anisotropic Media for Perpendicular and Heat Assisted Magnetic Recording
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Transcript of High Anisotropic Media for Perpendicular and Heat Assisted Magnetic Recording
High Anisotropic Media for Perpendicular and Heat Assisted
Magnetic Recording
Lesley Wears, Dave Newman
The magnetic recording industry is aiming to attain areal densities of around 1Tb/in2 before 2010
To attain densities beyond this and retain data integrity has dictated the adoption of very high anisotropy media necessitating in turn some form of “heat assist” for the recording process
The ideal medium for supporting magnetic recording at and beyond areal densities of 1Tb/in2 would be a mono-dispersion of highly anisotropic, non-interacting, single domain particles with TB < TC.
Patterned media produced using lithographic and/or etching processes
Self assembling arrays produced via complex chemical or biological routes
Dots silicon dioxide pillars and cobalt palladium layers
Sputtering onto a seed layer to orientate c axis
Post annealing and orientation of c axis by layering
20022002 Longitudinal mono-disperse particulate media produced by
Rapid Thermal Processing (RTP) of Co-Sputtered pre-curser material
20032003 In response to direction that industry is moving the process
has been modified to produce particulate perpendicular media
Our SolutionOur Solution
A combination of reactive sputtering and Rapid A combination of reactive sputtering and Rapid Thermal Processing TechnologiesThermal Processing Technologies
2. Power to Cobalt and Platinum targets switched off and thin Silicon Nitride protective overlayer deposited.
1. Cobalt Nitride reactively co-sputtered with unreactive Platinum on to glass substrate to produce precursor layer.
3. Precursor medium undergoes Rapid Thermal Processing in 8kWatt vacuum optical oven when
(a) Cobalt nitride disassociates with the release of Nitrogen which escapes by diffusion through overlayer
(b) Released Cobalt alloys with the Platinum
(c) The correct peak processing temperature develops the L10 phase with an orientated tetragonal structure
(c) PtCo condenses on substrate as a near monolayer of monodisperse particles
-6 0 6
-0.2
0
0.2
5000C
70W
Applied Field / kOe
-500
0
500
-6 0 6
5000C
70W
Applied Field / kOe
-0.2
0
0.2
5000C
40W
-500
0
500
5000C
40W
-500
0
500
5000C
30W
-0.2
0
0.2
5000C
30W
-500
0
500
5000C
20W
Ms
-0.2
0
0.2
5000C
20W
k
-0.2
0
0.2
5000C
50W
-500
0
500
5000C
50W
-500
0
500
5000C
60W
-0.2
0
0.2
5000C
60W
-0.2
0
0.2
5000C
40W
-500
0
500
5000C
40W
Optimum sputtering powers to the Co and Pt targets is determined by comparing the in and out of plane hysteresis loops as a function of composition. The following sequence shows the results of maintaining 50W to the Co target whilst varying that to the Pt target between 20W and 70W.
It is found that although Pt sputters much faster than Co the reactive nature of the CoN deposition process determines that the ratio of Co to Pt in the precursor films is optimised at 1:1 when the sputtering powers are near matched.
500
2500
20 40 60
40W
Cou
nts
500
2500
20 40 60 80
CoPtCoPt3
70W
500
2500
20 40 60
30W
2
0
1
2
3
4
30 45 60 75
In PlaneOut of Plane
Pt percentage in processed film
Hc
/ kO
e
Far
aday
Ro
tati
on
/ A
rb.u
nit
sF
arad
ay R
ota
tio
n /
Arb
.un
its
Applied Field / kOeApplied Field / kOe
200oC
-40 -20 0 20 40
300C
-40 -20 0 20 40
500C
450C
-40 -20 0 20 40
650oC
-3000
0
3000
-6 -3 0 3 6
Applied Field / kOe
Ms
-3000
0
3000
-6 -3 0 3 6
Applied Field / kOe
Ms
-3000
0
3000
-6 -3 0 3 6
500o
650o
300o
Applied Field / kOe
Ms
0
2500
5000
20 40 60 80 100
650C
Counts
0
2500
5000
20 40 60 80 100
500C
40 60 80 100
500C
650C
0
0.002
0.004
0.006
0.008
0.010
0 100 200 300 400
Linear Density / kfci
Normalised Noise Power
-2.0
-1.5
-1.0
-0.5
0
0.5
0 100 200 300 400 500
Linear Density /kfci
Normalised TAA
0
1
2
3
15.0 17.5 20.0 22.5
T1/2
/K1/2
Hc
/ kO
e
k
KVTB 25
0
0.015
0.030
0.045
0 100 200 300 400
Linear Density / kfci
Normalised Noise Power
-0.5
0
0.5
0 2 4 6
Field / kOe
M
-1.0
-0.6
-0.2
0 100 200 300 400
Linear Density / kfci
Normalised TAA
Probe Storage
0
300
600
900
1200
1500
0 2 4 6 8 10
100(m)-1
50m)-1
Voltage (V)
Max
imu
m T
emp
erat
ure
(K
)
300 400 500 600 700 8000
0.5
1
1.5
2
2.5
3x 10
5
Temperature (K)
Conductivity (1/(ohm.m))
ConclusionsConclusions
This media may be developed in a number of ways
(i) As a perpendicular media
(ii) As a Heat assisted recording media (HARM)
(iii) Substitute Fe for Co – Increase Anisotropic field and decrease particle size.
(iv) Magnetic patterned media
M. Jollie1, C.D. Wright2, M Aziz2, J. Miles 3 , D.Choo 4
1Coventry University2University of Exeter3Dept Computer Science University of Manchester. 4Nanomagnetics Ltd Bristol.
Acknowledgements:Acknowledgements: