Track width measurement in heat-assisted magnetic recording systems using the cross-track DC noise method

Abstract

This paper uses a cross-track DC noise measurement technique to determine the written track width in heat-assisted magnetic recording (HAMR). The method is approached as a simple, no-extra-hardware-required technique on a spin-stand to determine the written track width as well as the DC noise amplitude at the center track in a HAMR system. The track width data show the expected trends with changing laser operating current (Iop) and write current (Iw), and they are strongly correlated with track density capabilities and physical near-field transducer (NFT) peg width. The written track width is essentially defined by the Iop, which increases as Iop increases. The method is useful for comparing the magnetic responses of different writer pole or NFT peg geometries, as well as media design comparison to provide insight into the head/component necessary to improve HAMR system performance, which is useful HAMR recording parameters for head/media designers and test engineers.