Spin-stand measurements of time and temperature dependence of magnetic recordings

Abstract

Spin-stand experiments were performed to study the effect of temperature and demagnetizing fields on the stability of magnetic recordings. Tracks of varying linear bit densities were written on a low Mrδ medium that was heated in situ to different temperatures. The readback amplitude, which reflects the changes in the magnetization of the recordings, was observed from 32 ms to 12 h after the tracks were written. The readback amplitude was found to decay with time. The rate of decay increased at higher densities due to higher demagnetizing fields. A further increase in the decay rate was observed at higher temperatures. This increase in decay rate exceeded that predicted by proportional temperature scaling.

Low noise properties and thermal stability of Co-based thin film media for high density longitudinal recording

“…There have been many reports on thermal stability measurements involving conventional magnetometry [18], spinstand [18]- [21], and MFM measurements [22]. Most of media with adequate coercivity indicate no significant decay when observed at room temperature where measurement is a bit easier although still not very simple.…”

“…Most of media with adequate coercivity indicate no significant decay when observed at room temperature where measurement is a bit easier although still not very simple. Measurements at high temperatures have been made by P. Dhagat et al [21] for moderate linear densities; the disk was heated in situ with a lamp heater. We describe a method here which allows the disk to be removed from the spindle (for ex situ annealing) and replaced for measurement.…”

Media noise, nonlinear distortions, and thermal stability in high density recording

“…The demagnetization field is density-dependent, with the strongest demagnetization fields observed at high density regions of recorded data. The density dependence of decay rates was reported in several studies [7]- [9].…”

“…The estimates for typical thin-film media [5], [6] indicate that thermal fluctuations spontaneously reverse magnetization of magnetic grains having effective diameter of about 9-10 nm. The spontaneous magnetization reversal results in magnetization decay, which has been experimentally observed under various conditions [7], [8]. The magnetization decay is approximately linearly dependent on the logarithm of time and is expressed as percentage signal decay per decade of time.…”

Recent advances in the recording physics of thin-film media

“…grains is responsible for the signal decay that has been observed by various workers [40,[84][85][86][87]. To first order, one expects that the value K 1 V /k B T derived from, for example a dynamic coercivity experiment, correlates with the amount of signal decay of written magnetization patterns.…”