Increasing track density necessitates the use of narrower data reader widths, which combined with increasing linear density results in a significant reduction in the SNR of the read-back signal. In order to mitigate these effects we are developing heads based on giant-magneto-resistance (GMR) and tunneling-magneto-resistance (TMR) technology and working on the integration of analog front-end electronics directly at the read/write head. Another challenge arising from decreasing data track widths is track misregistration caused by changes in the media dimensions due to environmental effects and tension variations.
One way to mitigate such effects is to reduce the span of the head, i.e., move the read and write transducers closer together. However, decreasing the pitch between write transducers can lead to cross-talk between adjacent head elements. This effect can be minimized by careful design and finite element modeling, but still places a limit on the minimum pitch between elements . Figure 9 shows a micrograph of a section of a read/write head built using conventional technology.
With this technology, the physical size of the coils limits how much the pitch between elements can be reduced. To further reduce the transducer pitch, we are working on the development of planar head technologies, which allow elements to be staggered in the plane of the head and should allow adjacent track writing with write transducers that have a large enough physical spacing to avoid cross-talk effects.