Stephan Knappmann

Fabrication of a Micro Coil for Magneto-Optical Data Storage

Magnetic Amplifying Magneto-Optical System (MAMMOS) is a technique to substantially increase the data storage density of optical recording by a double layer media approach: a bottom recording TbFeCo layer, and a top GbFeCo layer used for domain spreading when a supporting magnetic field is applied. Using MAMMOS technique, the micro coil is fabricated for magneto-optical data storage.

Write head with a micro coil for magneto-optical data storage

To increase storage capacity, an advanced magneto-optical recording technology using high numerical aperture (NA) optics (NA>0.8) in combination with a micro coil creating a local magnetizing field has been investigated. For data recording, a beam of blue laser light locally heats up the magneto-optical storage layer, which is then magnetized by the micro coil. The micro coil therefore needs to be located at a very small working distance (<50 /spl mu/m) from the disks, which requires the magnetic coil to be mounted between the lens and the disk. Furthermore, the substrate has to be transparent to allow the laser beam to pass through the center of the magnetizing coil. The microcoil that has been developed has proven capable of creating the magnetic field required for magneto-optical recording, could operate at the required recording frequencies, and promises sufficient heat dissipation.

Thermo-resistive flight attitude measurements of flying heads in near field magneto-optical data storage

A thermo-resistive test head that uses thermo-resistors embedded in the air bearing surface (ABS) was created. Joule heating by the sensing current generates a heat flow across the head-disk spacing which highly depends on the distance between ABS and disk. Due to the thermal sensors located on each of the four corners of a slider, pitch, roll, and flying height variations may be measured.