Coherent vs. incoherent switching for elongated CoPt–O grains in high-anisotropy medium

Wu, Xiaowei; Veerdonk, R.J.M. van de; Lü, Bin; Weller, D.

doi:10.1016/j.jmmm.2006.01.076

Cited by 12 publications

(7 citation statements)

References 8 publications

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“…Helpful discussion with Hong-Sik Jung and the financial support of the WWTF project MA09-029 and Austrian Science Fund (FWF:) SFB ViCoM ( F4112-N13 ) is acknowledged. [34]. In the simulation a grain with a hexagon as basal plane with with D = 7 nm is assumed.…”

Section: Discussionmentioning

confidence: 99%

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Calculation of coercivity of magnetic nanostructures at finite temperatures

et al. 2011

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We report a finite temperature micromagnetic method (FTM) that allows for the calculation of the coercive field of arbitrary shaped magnetic nanostructures at time scales of nanoseconds to years.Instead of directly solving the Landau-Lifshitz-Gilbert equation, the coercive field is obtained without any free parameter by solving a non linear equation, which arises from the transition state theory. The method is applicable to magnetic structures where coercivity is determined by one thermally activated reversal or nucleation process. The method shows excellent agreement with experimentally obtained coercive fields of magnetic nanostructures and provides a deeper understanding of the mechanism of coercivity.

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Section: Discussionmentioning

confidence: 99%

“…The experimental data is extracted from the work of Wu et al [34]. In the paper the average grain diameter was given as 7 nm.…”

Section: (B) Thickness Dependence Of the Coercive Fieldmentioning

confidence: 99%

Calculation of coercivity of magnetic nanostructures at finite temperatures

et al. 2011

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“…To achieve a large SNR in recording media, the grains are supposed to reverse their magnetization coherently. In this case the magnetic switching volume is the same as the physical particle volume observed from transmission electron microscopy (TEM) [6], even the particle may consist of many grains in its volume. Increasing film thickness increased the thermal stability factor due to increased magnetic switching volume [7,8].…”

Section: Introductionmentioning

confidence: 99%

Microstructural evolution and magnetization reversal mechanism of CoPt films with perpendicular magnetic anisotropy

Pandey

Chen

et al. 2008

J. Phys. D: Appl. Phys.

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Microstructural evolution and magnetization reversal mechanisms of perpendicular magnetic anisotropic Co72Pt28 films were investigated. Results showed that in the initial stage of film growth, the Co72Pt28 film was continuous and followed a dome-shaped structure with increasing film thickness. When the film thickness further increased above a certain critical value, the film growth acquired an inverted frustum shape structure and increased the intergranular magnetic interaction. The magnetization reversal mechanism showed a strong dependence on microstructures. The magnetization reversal followed the domain wall motion behaviour when the film was continuous and deviated towards the Stoner–Wohlfarth (S–W) model in the dome-shaped regime. A further deviation away from the S–W model was observed, when the film acquired an inverted frustum shape structure in order to minimize the surface energy.

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“…This critical thickness has been determined both experimentally and theoretically. Theoretically, it is 7,18 d C ~4(AK {1 ) 1=2 (3…”

Section: Writing Limitmentioning

confidence: 99%

“…For the conventional recording, the effective write field gradient (dH/dx) eff is determined simply by the write head. For HAMR, it can be expressed as follows 153 dH dx eff &{ dH C dT dT dx (18) where dH C /dT is the medium coercivity dependence of temperatures, and dT/dx is the spatial gradient of temperature in the medium heated by the local incident light. This effective field gradient is much stronger than that for the conventional magnetic heads.…”

Section: Heat Assisted Recordingmentioning

confidence: 99%

Development of high density magnetic recording media for hard disk drives: materials science issues and challenges

Gan¹,

Ren²,

Xiao³

et al. 2009

International Materials Reviews

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The tremendous increase in areal density of hard disk drives is mainly ascribed to harmonic development between magnetic recording media and heads in their scaling, especially allowing a commercial transition from the longitudinal to perpendicular recording system. This paper reviews the main features, recent breakthroughs and future potentials of both the longitudinal and the perpendicular media from a viewpoint of materials science. Special attention is firstly paid to the 'trilemma' problem for the media, i.e. the compromise among writability, thermal stability and signal to noise ratio (SNR). The evolution of media materials these years are then addressed with emphasis on the thermodynamic origin of magnetically induced phase separation of Co-Cr based alloys, which governs media noise and coercivity, and its applications to the current longitudinal media. The materials challenges for media to achieve 500 Gb in. 22 and above are further predicted from the viewpoints of thermal stability improvement and microstructure control of media materials, and their engineering issues have been discussed for the current Co-Cr based alloys, potential FePt and CoPt ordered, phase separated Co-W based alloys and magnetic rare earth compounds. Finally, the future media approaching 1 Tb in. 22 and beyond are addressed with respect to the principles, progress, engineering challenges and future directions.

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Coherent vs. incoherent switching for elongated CoPt–O grains in high-anisotropy medium

Cited by 12 publications

References 8 publications

Calculation of coercivity of magnetic nanostructures at finite temperatures

Calculation of coercivity of magnetic nanostructures at finite temperatures

Microstructural evolution and magnetization reversal mechanism of CoPt films with perpendicular magnetic anisotropy

Development of high density magnetic recording media for hard disk drives: materials science issues and challenges

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