Because conventional perpendicular recording is now reaching its useful limits, the hard drive industry is heavily invested in several alternative recording technologies. The majority of these configurations (such as heat-assisted magnetic recording, microwave-assisted magnetic recording, and bit-patterned magnetic recording) secure their advantages by solving essential problems in the writing process. In contrast, two-dimensional magnetic recording (TDMR) expends its essential focus on the reading process, by providing multiple looks at adjacent written information via multiple read sensors on one slider. This "sleeper" technology was rather abruptly recognized, at a recent conference of recording technologists, as a leading contender for the next generation of HDD technology. While generally thought of as a more conventional option than the alternatives, TDMR nevertheless has profound impact on magnetic component design and on elements of the entire supporting recording system. These impacts will be reviewed in detail from both a magnetic system and a signal-processing perspective. Innovations in linear and nonlinear system identification techniques in two dimensions will be proposed and illustrated.
Video of Jonathan Coker's IEEE Magnetics distinguished lecture