Thermal decay in high density disk media

Zhang, Yun; Bertram, H.N.

doi:10.1109/20.718543

Cited by 63 publications

(28 citation statements)

References 10 publications

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“…In the last years the problem of how to correctly introduce temperature induced fluctuations into the equation of motion of a magnetic system has gained in importance [52][53][54][55][57][58][59][60][61]. Effects of thermal activation can be included into the micromagnetic calculus by adding a time-dependent random thermal field ( ) i t ξ to the effective magnetic field H -∂ / ∂M with the Hamiltonian H [54][55][56][57].…”

Section: Micromagneticsmentioning

confidence: 99%

Influence of the lattice discreteness on magnetic ordering in nanostructures and nanoarrays

Vedmedenko¹

2007

Physica Status Solidi (b)

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.+ aThe article attempts to analyze the effect of lattice discreteness on the magnetic ordering in nanostructures and nanoarrays. The discussion starts with a basic introduction of the theoretical methods for the description of the magnetic ordering. Next it is shown that the discrete nature of an atomic lattice may lead to the size-driven reorientation of magnetization in nanoparticles, i.e., the magnetization direction can be changed by shrinking the lateral size, keeping the thickness fixed. It is demonstrated that in finite nanomagnets the shape anisotropy can be divided into the discrete and continuum contributions. Then the orientation of magnetic domain walls in low-symmetry objects is discussed. It is shown theoretically that in nanomagnets of monolayer thickness the mechanism of the orientation of domain walls is different from that of bulk systems and is mainly determined by the discreteness of the atomic lattice and the exchange energy. In the last part the theoretical study of magnetostatically interacting nanoarrays is presented. Special attention is paid to the influence of the underlaying lattice symmetry and the higher order multipolar terms on the magnetic ordering. It is demonstrated that the multipole-multipole interactions lead to an enhancement/decrease of the coercivity in arrays with in-plane/out-of-plane magnetization, respectively. In each section of the manuscript the agreement between the theory and recent experimental results is analyzed.

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Section: Micromagneticsmentioning

confidence: 99%

Influence of the lattice discreteness on magnetic ordering in nanostructures and nanoarrays

Vedmedenko¹

2007

Physica Status Solidi (b)

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“…For switching of isolated Stoner-Wohlfarth particles by coherent rotation, would be the particle volume, but for thin-film media where interactions exist and switching may occur by other modes, the physical interpretation of is less clear. Nevertheless, experiment has shown that stability degrades as the product of the remanent moment and magnetic layer thickness, , decreases [3], [5], and it is typically assumed that the microstructure has columnar grains and therefore fairly constant grain diameter with thickness. It has been shown by modeling that the effect of exchange between grains improves the stability [6], but it also increases the Manuscript noise so ultimately longitudinal media will need to minimize the exchange interaction.…”

Section: Introductionmentioning

confidence: 99%

Microstructure and thermal stability of advanced longitudinal media

Doerner¹,

Tang²,

Arnoldussen³

et al. 2000

IEEE Trans. Magn.

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Thermal stability will ultimately limit the maximum areal density achievable with conventional longitudinal recording.The key aspects of the media microstructure contributing to thermal stability are the grain size and grain size distribution, alloy composition, alloy segregation, lattice defects and strain. Grain size distributions are created by the random nucleation processes occurring during media deposition. For media on glass substrates, -axis in-plane preferred orientation can be achieved with either Co (1120) or (1010) planes parallel to the substrate surface. Improved squareness, , is observed with the (1120) orientation due to stronger crystallographic texture, however, larger changes in coercivity with decreasing magnetic layer thickness are observed compared to (1010). Continued increases in areal density will require tighter grain size distributions and improved microstructural control of very thin magnetic layers.

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“…Panel (c) is a plot of thermal stability factor distribution in this thin film media sample. The distribution is well represented by the solid line that has a standard deviation that is 16% of the mean results using recording measurements [6], [7]. Therefore interactions between grains (exchange coupling) [8] are exerting a very strong effect on reducing the energy barrier distribution width.…”

Section: Discussionmentioning

confidence: 99%

Measurement of thermal stability factor distribution in thin film media

2001

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An experimental method of measuring the distribution of thermal stability factors, , in thin film hard disk drive media samples using a vibrating sample magnetometer (VSM) is described. The measurement results indicate that energy barrier distribution width is less than intrinsic physical volume distribution.Index Terms-Magnetic measurement, thermal stability, thin film media, vibrating sample magnetometer.

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Thermal decay in high density disk media

Cited by 63 publications

References 10 publications

Influence of the lattice discreteness on magnetic ordering in nanostructures and nanoarrays

Influence of the lattice discreteness on magnetic ordering in nanostructures and nanoarrays

Microstructure and thermal stability of advanced longitudinal media

Measurement of thermal stability factor distribution in thin film media

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