Geometrical Scaling Limits of Heat-Assisted Magnetic Recording

System-level requirements for heat-assisted magnetic recording at high areal density are presented in this article. The primary factors that affect bit error rate (BER) are spatial, or media, signal-to-noise ratio (SNR), reader SNR, and channel bit density (CBD). Spatial SNR is largely determined by the interaction between the writer properties and the media properties. For example, how well the thermal gradient matches the grain size. Spatial SNR also depends on how well the reader cross-track resolution matches the track pitch, and the quality of the written pattern. For any given level of spatial SNR, there exists a combination of CBD and reader SNR that results in the desired level of performance. This article elucidates some of the tradeoffs that may be needed to maintain BER as areal density increases, for different bit aspect ratio scenarios. For very high areal density, we show that the geometrical requirements are extremely aggressive, which will most likely require significant invention in head and drive architecture design.