Bernardus A. J. Jacobs

High Performance Media for Phase Change Optical Recording

We discuss various mechanisms that lead to a high crystallization rate of the recording layer in a phase change disk. The role of interface layers, recording layer composition and its thickness is especially emphasized. Disks with a data bit rate beyond 40 Mbit/s have been realized.

Magneto-optical recording in Co/Pt multilayers

In this paper the magnetic and magneto-optical properties as well as the recording performance of Co/Pt layered structures are described. Two different structures are investigated: One with 4 A Co and 9 A Pt layers and the other with 4 A Co and 18 A thick Pt layers. We show with Lorentz microscopy that very regular domains can be written in these layers and we relate these results to the measured recording performance. Domain patterns are written in two different ways, with laser modulation (LM) and magnetic field modulation (MFM). With LM very regularly shaped domains are formed. With MFM we find a strong tendency for subdomain formation.

Improved High-Density Phase-Change Recording

By using a simple write strategy we have found that a wide range of linear velocities can be covered for direct overwrite in high-density phase-change recording. This is especially advantageous for data recording where the application of constant angular velocity facilitates fast seek and short random-access times. In the case of repeated overwriting, material flow will limit the number of cycles, particularly if a fixed pseudo-random data pattern is used. We studied how a random bit shift can reduce this problem and found that a relatively large shift of up to 100 bytes was required. Using these techniques in an optimized disc structure we achieved more than 100,000 overwrite cycles on a 2.6 Gbyte 12 cm phase-change disc.