Thermal stability of recorded information at high densities

Charap, S. H.; Lu, Peilin; He, Yanjun

doi:10.1109/20.560142

Cited by 501 publications

(196 citation statements)

References 18 publications

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“…2 The tetragonal phase of an FePt system is of particular interest because of the high magnetocrystalline anisotropy ͓K U ϳ͑6.6− 10͒ ϫ 10 7 erg/ cm 3 ͔ that should allow the use of smaller particles, but yet avoid thermal instabilities that give rise to superparamagnetic ͑SPM͒ behavior. 3,11 Since the medium magnetic stability is controlled by the ratio of the magnetic anisotropy energy, K U V, to the energy of thermal fluctuations, k B T, where K U is the recording layer magnetic anisotropy energy density and V is the thermal activation volume, which corresponds approximately to the volume of a single magnetic grain, and the k B T are Boltzmann's constant and the temperature, respectively. The ratio K U V / k B T is kept at a value of 50-70 to ensure 10-15 years data stability.…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence and magnetocrystalline anisotropy studies of self-assembled L10-Fe55Pt45 ferromagnetic nanocrystals

Varanda

Jafelicci

Imaizumi

2007

Journal of Applied Physics

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Temperature dependence and uniaxial magnetocrystalline anisotropy properties of the chemically synthesized 4 nm L1 0 -Fe 55 Pt 45 nanoparticle assembly by a modified polyol route are reported. As-prepared nanoparticles are superparamagnetic presenting fcc structure, and annealing at 550°C converts the assembly into ferromagnetic nanocrystals with large coercivity ͑H C Ͼ 1 T͒ in an L1 0 phase. Magnetic measurements showed an increasing in the ferromagnetically ordered fraction of the nanoparticles with the annealing temperature increases, and the remanence ratio, S = M R / M S Х 0.76, suggests an ͑111͒ textured film. A monotonic increase of the blocking temperature T B , the uniaxial magnetocrystalline anisotropy constant K U , and the coercivity H C with increasing annealing temperature was observed. Magnetic parameters indicate an enhancement in the magnetic properties due to the improved Fe 55 Pt 45 phase stabilizing, and the room-temperature stability parameter of 67, which indicates that the magnetization should be stable for more than ten years, makes this material suitable for ultrahigh-density magnetic recording application.

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Section: Introductionmentioning

confidence: 99%

Temperature dependence and magnetocrystalline anisotropy studies of self-assembled L10-Fe55Pt45 ferromagnetic nanocrystals

Varanda

Jafelicci

Imaizumi

2007

Journal of Applied Physics

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“…2 recording environment, 8 due to nonnegligible interbit stray fields. For Co-based media, K u Ϸ2 ϫ10 6 erg/cm 3 .…”

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confidence: 99%

Nanocomposite CoPt:C films for extremely high-density recording

Liu

Möser

et al. 1999

Applied Physics Letters

162

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Nanocomposite CoPt:C films were investigated as potential media for extremely high-density recording. An annealing temperature of over 600 °C is necessary to form nanocomposite CoPt:C films consisting of C matrix and fct CoPt nanocrystallites with grain sizes of 8–20 nm and coercivities of 3–12 kOe. Coercivity and grain size increase with increasing annealing temperature and decreasing C concentration and they are insensitive to film thickness. The average activation volumes are about 0.9×10−18 cm3. The properties of these nanocomposite CoPt:C films can be tailored to satisfy the thermal stability, coercivity, and media noise requirements for extremely high-density recording.

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“…At achieved densities of 45 Gbit/in 2 the mean grain diameter is about 9 nm. At this diameter the estimated ratio of anisotropy energy to thermal energy, K u V/k B T, is only about 70-80, which is close to the estimated requirement of K u V/k B T >60 for stability over a ten year period [269,274].…”

Section: Recording Media Noise and Scaling Limitationsmentioning

confidence: 71%