Jason S. Goldberg

Degaussing of Write Heads in Perpendicular Magnetic Recording

This paper introduces the idea of degaussing of perpendicular magnetic recording (PMR) heads, the approach generally accepted by the magnetic recording industry. Basic theoretical aspects of degaussing are discussed. A simplified approach based on write current turnoff is first studied. Second, an advanced degaussing method involving a sequence of write pulses of opposite polarities and decaying amplitude is analyzed using micromagnetic modeling tools. Dependences on degauss waveform parameters like frequency and duration are studied to provide guidance to find optimal solutions for reliable writer degaussing.

Method for Analysis of On-Track and Off-Track Shielded Magnetic Write Head Recording Performance Based on Write Current Waveform Shaping

This paper introduces a method of simultaneous analysis of on-track and off-track recording performance for arbitrary write current waveforms using a side-shielded writer. The method successfully combines accurate micromagnetic modeling of the recording process on a nanosecond time scale and analytical estimates of recording performance. Off-track performance is evaluated using a media thermal barrier approach defined on very long time scale. The strength of the method is validated for various parameters of the write current waveform, such as steady state current and overshoot amplitude. The obtained modeling results match experimental results elucidated in literature. This study enables HDD system optimization, permitting recording optimization for shielded write head designs with various write current waveform shapes.