Bit patterned media optimization at 1 Tdot/in2 by post-annealing

Hellwig, Olav; Marinero, Ernesto E.; Kercher, Dan; Hennen, T.; McCallum, Andrew; Dobisz, Elizabeth A.; Wu, Tong; Lillé, J.; Hirano, T.; Ruiz, Ricardo; Grobis, M.; Weller, D.; Albrecht, T. R.

doi:10.1063/1.4896667

Cited by 14 publications

(9 citation statements)

References 22 publications

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“…However, in the discrete island BPM geometry, with distinct trench regions in between islands, the thermally activated Cr diffusion is much more extensive. In a previously reported annealing study we focused on Cr-rich Co70Cr18Pt12 media and optimized annealing temperature and time for that specific case [39]. Here we note that with other CoCrPt media layer compositions fabricated at 1 Td/in 2 BPM we have obtained HC above 8 kOe and iSFD/HC values below 5% (see Fig.…”

Section: Bsupporting

confidence: 50%

Bit-Patterned Magnetic Recording: Theory, Media Fabrication, and Recording Performance

et al. 2015

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Bit Patterned Media (BPM) for magnetic recording provides a route to thermally stable data recording at >1 Tb/in 2 and circumvents many of the challenges associated with extending conventional granular media technology. Instead of recording a bit on an ensemble of random grains, BPM is comprised of a well ordered array of lithographically patterned isolated magnetic islands, each of which stores one bit. Fabrication of BPM is viewed as the greatest challenge for its commercialization. In this article we describe a BPM fabrication method which combines rotary-stage e-beam lithography, directed self-assembly of block copolymers, self-aligned double patterning, nanoimprint lithography, and ion milling to generate BPM based on CoCrPt alloy materials at densities up to 1.6 Td/in 2 (teradot/inch 2 ). This combination of novel fabrication technologies achieves feature sizes of <10 nm, which is significantly smaller than what conventional nanofabrication methods used in semiconductor manufacturing can achieve. In contrast to earlier work which used hexagonal closepacked arrays of round islands, our latest approach creates BPM with rectangular bitcells, which are advantageous for integration of BPM with existing hard disk drive technology. The advantages of rectangular bits are analyzed from a theoretical and modeling point of view, and system integration requirements such as provision of servo patterns, implementation of write synchronization, and providing for a stable head-disk interface are addressed in the context of experimental results. Optimization of magnetic alloy materials for thermal stability, writeability, and tight switching field distribution is discussed, and a new method for growing BPM islands from a specially patterned underlayer -referred to as "templated growth" -is presented. New recording results at 1.6 Td/in 2 (roughly equivalent to 1.3 Tb/in 2 ) demonstrate a raw error rate <10 -2 , which is consistent with the recording system requirements of modern hard drives. Extendibility of BPM to higher densities, and its eventual combination with energy assisted recording are explored.Index Terms-Bit patterned media, hard disk drive, block copolymer, self-assembly, double patterning, e-beam lithography, sequential infiltration synthesis, nanoimprint lithography, templated growth, thermal annealing, Co alloys, magnetic multilayers, interface anisotropy, magnetic recording, write synchronization, prepatterned servo, areal density.

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Section: Bsupporting

confidence: 50%

Bit-Patterned Magnetic Recording: Theory, Media Fabrication, and Recording Performance

et al. 2015

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“…15,21 Recently, most progress has been achieved by moving from pre-patterned substrates and subsequent blanket-deposition of the magnetic material to BPM based on full-film deposition with subsequent post-etching for forming isolated magnetic island BPM. 2,22,23 These systems completely avoid the noise and demagnetization challenges that trench material in BPM based on pre-patterned substrates presents.…”

Section: -2mentioning

confidence: 99%

Influence of stray fields on the switching-field distribution for bit-patterned media based on pre-patterned substrates

Pfau

Günther

Guehrs

et al. 2014

Applied Physics Letters

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Using a direct imaging method, we experimentally investigate the reversal of magnetic islands in a bit-patterned media sample based on a pre-patterned substrate. Due to systematic variation of the island distances in the media, we are able to study the influence of the dipolar interaction on the switching-field distribution of the island ensemble. The experimental findings are explained by an analytical magnetostatic model that allows us to quantify the different components of the demagnetizing field in the system and to distinguish intrinsic and dipolar broadening of the switching-field distribution. Besides the well-known dipolar broadening due to stray fields from neighboring islands, we find strong influence from the magnetized trench material on the island switching.

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“…Enormous efforts are devoted to the development of magnetic materials with perpendicular magnetic anisotropy (PMA) for bit-patterned media (BPM) [1][2][3][4][5][6][7] and magnetic random access memory (MRAM). [8][9][10][11][12][13][14][15] In fact, materials with PMA have higher magnetic anisotropy energy compared to their counterparts with in-plane anisotropy.…”

Section: Introductionmentioning

confidence: 99%

Temperature effect on exchange coupling and magnetization reversal in antiferromagnetically coupled (Co/Pd) multilayers

Sbiaa

Al‐Omari

Kharel

et al. 2015

Journal of Applied Physics

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Sbiaa, R.; Al-Omari, I. A.; Kharel, Parashu R.; Ranjbar, M.; Sellmyer, David J.; Akerman, J.; and Piramanayagam, S. N., "Temperature effect on exchange coupling and magnetization reversal in antiferromagnetically coupled (Co/Pd) multilayers" (2015). Magnetization reversal of antiferromagnetically coupled (AFC) soft and hard (Co/Pd) multilayers was studied as a function of temperature. While the hard [Co(0.3 nm)/Pd(0.8 nm)] Â10 was kept unchanged, the softness of the [Co(t)/Pd(0.8 nm)] Â3 was controlled by varying the thickness t of the Co sublayer. Clear two-step hysteresis loops were observed for all the investigated multilayers with t ranging between 0.4 and 1 nm. The spin reorientation of the soft layer magnetization from in-plane direction to out-of-plane direction was investigated from 50 to 300 K. The antiferromagnetic field H AFC measured from the shift of the minor hysteresis loop reveals a good agreement to the quantum-well model. From the out-of-plane hysteresis loop of the uncoupled soft layer, its magnetization shows an in-plane orientation for t ! 0.6 nm. The strong H AFC helps to induce an out-of plane orientation of the soft layer with a linear decrease of its coercivity with temperature. These investigated structures show the possibility to reduce the unwanted stray field and improving the out-of-plane anisotropy even for relatively thicker soft layer. V C 2015 AIP Publishing LLC.

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Bit patterned media optimization at 1 Tdot/in2 by post-annealing

Cited by 14 publications

References 22 publications

Bit-Patterned Magnetic Recording: Theory, Media Fabrication, and Recording Performance

Bit-Patterned Magnetic Recording: Theory, Media Fabrication, and Recording Performance

Influence of stray fields on the switching-field distribution for bit-patterned media based on pre-patterned substrates

Temperature effect on exchange coupling and magnetization reversal in antiferromagnetically coupled (Co/Pd) multilayers

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