High speed magnetic recording

Abstract

The maximum recording speed of a magnetic data storage device depends on the components in the recording channel, viz. electronics, interconnects, heads and media. The projected increase in device data rate (6-fold in 5 years) is that for the electronics (silicon switchfold in 5 years). Driving the write head meets with "driving point impedance" limitations, linking the required MMF, the interconnect and head inductance, supply voltage and write current switching speed. Novel write drivers can break this link.Interconnect limitations and distributed readlwrite electronics are discussed. Write field waveforms and their dependence on the write current are presented. Various ways of improving the head switching time are treated. Finally, for the projected data rate increase to materialize, one has to solve all component limitations virtually simultaneously.

Dynamics of Barkhausen jumps in disordered ferromagnets

“…Better understanding of the dynamic process of Barkhausen jumps in magnetic recording materials can, therefore, be very useful in the development of novel technology for future ultrahigh density and high data rate recording. 9 Barkhausen noise is caused by movement of magnetic domains or avalanches. These domains evolve collectively, exhibiting nonequilibrium collective behavior in the system driven far from equilibrium.…”

Dynamic anisotropy of thin Permalloy films measured by use of angle-resolved pulsed inductive microwave magnetometry

“…The high-frequency magnetic properties of highpermeability films have become of increased importance as the internal data-transfer rate of disk drives approaches 1 1 Gbit/ s. It is particularly important that the permeability, as reflected by a small magnetic anisotropy, does not diminish with operational frequency. One promising method for determining the high-frequency permeability of soft magnetic films uses the pulsed inductive microwave magnetometer ͑PIMM͒.…”

Sub-nanosecond non-Arrhenius magnetic switching in perpendicular multilayers

“…At the present data-rate of about 300-400 Mbit/s this response time is in the nanoseconds regime, and at 40% annual growth in data rate, sub-nanosecond switching will soon be needed [1]. On that time scale thermally activated processes are suppressed and the magnetization reversal is expected to be dominated by precessional switching [6], [7].…”