Steven L. Naberhuis

Thermal stability of magneto‐optic quadrilayers

The thermal stability of sputtered TbFeCo thin films in magneto‐optic quadrilayer structures containing Si3N4, SiO, and SiO2 dielectrics has been examined. The observed changes in coercivity upon annealing are attributed to two parallel mechanisms: structural relaxation in the amorphous magnetic alloy and preferential oxidation of Tb at the TbFeCo/SiO and TbFeCo/SiO2 interfaces. Kinetic modeling has revealed that a spectrum of activation energies is required to explain the relaxation data, whereas a single activation energy of 1.65 eV describes the oxidation process.

Dual stripe magnetoresistive heads for high density recording

The design and recording performance of dual stripe magnetoresistive read/inductive write heads with read widths of 4 /spl mu/m and write widths of 4.5 /spl mu/m are described. A linear density of 75 kfci (D50) was measured in heads with shield-to-shield spacing of 420 nm and 70 nm of dielectric separating the two magnetoresistive stripes. Large signal amplitude, linear cross-track profile, and good second harmonic suppression are observed in accordance with theoretical expectations. Readback waveforms contain little baseline shift and the ratio of positive to negative peak amplitudes is very close to unity. Stable signals are seen for heads with and without exchange stabilization. Conductor topography in the read head is replicated in the write head and can adversely affect cross-track behavior. Non-planarity of the write head must be considered in the design of shared pole magnetoresistive heads. >

Measured fields and performance of recording heads

A method is presented for obtaining the longitudinal magnetic field produced by recording heads. The method entails the use of a microloop to directly measure the perpendicular field Hy across the gap region of the head and the calculation of the longitudinal field Hx using a transform of Hy(x). This method has been applied to the study of narrow‐track, thin‐film heads. The ability to predict the shape of the readback waveform from a measurement of the head field is demonstrated.

Magnetooptic Quadrilayer Reliability And Performance

The stability of magnetooptic recording films based on rare earth - transition metal alloys has been investigated. Experimental results show two distinct degradation processes, one of which has been identified as oxidation of the active layer, the other of which appears to be a thermally activated relaxation of the microstructure. Performance data are presented for newly developed, stable structures which exhibit virtually unchanged 55-60 dB C/N ratios after annealing at 200 degrees centigrade in air. Environmental stability is discussed.

An ultra-compact electron-beam column

In this paper, an electron optical system with an array of columns was developed for an electron-beam addressable data storage device that has the form factor of compact flash and capacity > 10 GB. The columns were analyzed with a single Spindt emitter and a three-aperture focusing structure that focuses the beam into a 40 nm core that contains /spl sim/ 60% of the beam current and a tail that spreads to several hundred nanometers. The focusing structure and the emission characteristics for Spindt emitters were presented. An extended electron source that consists of an array of regularly or randomly distributed point emitters which consists of a randomly distributed hemi-spherical poly-silicon nodules (NPS) with 20 /spl plusmn/ 5 nm radius. The physical and electron emission characteristics of NPS were also presented. A novel electron optical column to focus the emission from the NPS extended electron source into a diameter < 30 nm was developed.