Novel magnetic characterization of the head-medium interface in metal particle tape systems

The head-medium noise of modern metal particle tape systems, which results from spacing fluctuations during the recording of data, dominates the mediu m noise of today's advanced digital tape. Traditionally, characterization o f the head-medium interface has been performed by using interferometry or a tomic force microscopy (AFM) measurements of the tape surface roughness. Ho wever, surface roughness measurements on two advanced metal particle (MP) t ape media displayed no correlation with the tape medium noise characteristi cs. A new insight into the impact of the tape load-bearing surface distribu tion on the head-tape spacing variation explained the shortcomings of the r oughness measurements to gauge the medium noise. Assessing the performance and characteristics of the head-medium interface requires a new methodology . To satisfy this need, a novel magnetic recording measurement is presented that offers a direct and complete characterization of the head-medium inte rface. Measured data show excellent correlation with the noise power spectr al density of square-wave recordings for several tape media. In addition, t he measurement revealed that long wavelength components dominate the MP tap e head-medium noise, resulting in a decrease of the playback broad-band noi se voltage power for recordings with shorter wavelength. The measurement te chnique provides new insight into the head-medium interface spatial charact eristics.