Greater than 14 Gb/in/sup 2/ spin valve heads

Tong, Ho‐Ming; Shi, X.; Liu, F.; Qian, C.; Dong, Z.W.; Yan, X.; Barr, Robert C.; Miloslavsky, L.; Zhou, Shihong; Perlas, J. A.; Prabhu, Prashanth; Mao, Ming; Funada, S.; Gibbons, M.; Leng, Qunwen; Zhu, Jian‐Gang; Dey, Subrata Kumar

doi:10.1109/20.800895

Cited by 27 publications

(11 citation statements)

References 7 publications

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“…However, in most of the cases theories were limited to specific problems where intricate structures at the interfaces were simplified. Until now, EB effects have been exploited in several technological applications such as read head of recording devices [39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54], magnetoresistive random access memories (MRRAM) [55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76] and it has been proposed for the technological applications in stabilizing magnetization of superparamagnetic nanoparticles [77,78,79,80] or to improve coercivity and energy product of the permanent magnets [81,82,83,84].…”

Section: Introductionmentioning

confidence: 99%

Exchange bias effect in alloys and compounds

Giri

Patra

Majumdar

2011

J. Phys.: Condens. Matter

320

225

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Abstract. The phenomenology of exchange bias effects observed in structurally single-phase alloys and compounds but composed of a variety of coexisting magnetic phases such as ferromagnetic, antiferromagnetic, ferrimagnetic, spin-glass, clusterglass, disordered magnetic states are reviewed. The investigations on exchange bias effects are discussed in diverse types of alloys and compounds where qualitative and quantitative aspects of magnetism are focused based on macroscopic experimental tools such as magnetization and magnetoresistance measurements. Here, we focus on improvement of fundamental issues of the exchange bias effects rather than on their technological importance.

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Section: Introductionmentioning

confidence: 99%

Exchange bias effect in alloys and compounds

Giri

Patra

Majumdar

2011

J. Phys.: Condens. Matter

320

225

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“…Thus, we believe that to achieve very high track densities, the use of a microactuator is crucial. In this paper we show that by properly scaling of our Dual-Synthetic-Spin-Valve (DSSV) [3], we have achieved recording at BAR's as small as 5.7 (Table I), and that the use of a microactuator can improve the areal density achievement even further. Manuscript In this work, recording characterization was carried out at the ID (0.8 inches in radius) of disks while rotating at 3000 RPM.…”

Section: Introductionmentioning

confidence: 94%

“…The reader element was a DSSV [3]. The write head was fabricated via conventional photolithography and wafer pole trimming used in currently available commercial products ( Fig.…”

Section: Experimental Conditionsmentioning

confidence: 99%

“…Recent areal density demonstrations at 13.5 [1]- [3], 20.3 [4], 20.9 [5], 26.5 [6], 35.3 [7], 36 [8], [9], 50 [10] and 63.2 Gb in have shown that the annualized areal density growth rate can be increased to as high as 175%, as shown in Table I. Although, the areal density is growing so fast, recently it has been more and more difficult for the linear density to keep up with this rate of growth.…”

Section: Introductionmentioning

confidence: 99%

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Demonstration and characterization of greater than 60 Gb/in/sup 2/ recording systems

et al. 2001

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We have successfully demonstrated longitudinal recording at areal densities greater than 60 Gb in 2 at data rates as high as 160 Mbps (20 MB/s) and at a Bit-Aspect-Ratio (BAR) of 5.7, using merged inductive-write/spin-valve-read heads with microactuators on low noise thin film disks. The heads were fabricated with the standard photolithography and wafer pole trimming used in currently available commercial products. At track densities of 60 KTPI and higher, traditional servoing mechanism will not be adequate. With the use of a microactuator, we can further improve the track density by 15%, the linear density by 10% and the areal density by more than 20%. Thus, using microactuator with the 50 Gb in 2 head/media combination we have increased our areal density achievement up to 63.2 Gb in 2 .

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“…The heads in particular already use ( Fig. 2 of [13]) a high initial susceptibility that brings the magnetization only up to M 1 =M s % 0:5, with a gradual increase from this value to the saturation M s , so that nothing important will be changed if amorphous films, subdivided into separate discs, are used.…”

Section: Superparamagnetismmentioning

confidence: 99%

The Special Role of Magnetization Curling in Nanoparticles

Aharoni

2002

phys. stat. sol. (a)

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A qualitative change can occur, in a certain particle size, if the magnetization reverses by the curling mode, as demonstrated by superparamagnetic spheres, and by the initial susceptibility of ideally-soft spheres and disks. The theory of exchange resonance modes in small ferromagnetic spheres is extended to the case of a sphere whose centre is not ferromagnetic, as is the case when the magnetic particle is grown around a non-magnetic nucleus, such as the fine particles of the alloys of Fe, Co, and Ni that are made around a nucleus of a noble metal. A first-order calculation leads to a negligible modification of the eigenvalues for the inner radius used in the experiments. For larger holes, the change can be measurably large for some modes. IntroductionThe theory of micromagnetics has never been able [1] to account for the magnetization processes in bulk ferromagnets. It is commonly believed that these processes are mostly governed by crystalline imperfections in hard materials, and by surface roughness and internal voids in soft materials. Both types help the nucleation of reversed domains on the one hand, and hinder the motion of the walls on the other hand. In both cases, however, the mechanisms are not sufficiently clear, and there is no satisfactory theory for them. There are many numerical simulations, but the results always look as if something is still missing there [2], so that they do not even seem promising yet, and it is not really known how to proceed.The situation is much better with fine ferromagnetic particles, for which it is energetically unfavorable to subdivide into domains, thus eliminating the most difficult theoretical problem of nucleation and growth of reversed domains. Theoretical nucleation fields are [3] close to the experimental coercivities of nearly-perfect whiskers for small whisker radius, but are off by several orders of magnitude for larger radii, thus indicating that the effect of body and surface imperfections is less important in fine particles than it is in larger ones. The computer resources necessary for numerical study of particles, by subdividing them into a sufficiently fine mesh, is also manageable when the particles are not too large. Moreover, there are now several experimental studies of individual particles, with which it should be easy to compare the theoretical results, without the problem of interactions between particles that complicated the analysis of older experiments. And there are some analytic results for ideal particles that can be used as a start and a guidance for the study of less perfect particles.It should thus seem natural for numerical micromagnetics to concentrate on extending the analytic results, by studying the effects of imperfections, and of other phenomena neglected in the old theory, such as surface anisotropy, magnetostriction, etc. For some historical reasons, however, numerical computations have been [2] mostly search-

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Greater than 14 Gb/in/sup 2/ spin valve heads

Cited by 27 publications

References 7 publications

Exchange bias effect in alloys and compounds

Exchange bias effect in alloys and compounds

Demonstration and characterization of greater than 60 Gb/in/sup 2/ recording systems

The Special Role of Magnetization Curling in Nanoparticles

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