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 medium noise of today's advanced digital tape. Traditionally, characterization of the head-medium interface has been performed by using interferometry or AFM measurements of the tape surface roughness. However, surface roughness measurements on two advanced metal particle tape media displayed no correlation with the tape medium noise characteristics. A new insight into the impact of the tape load-bearing surface distribution on the head-tape spacing variation explained the shortcomings of the roughness 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 interface. Measured data show excellent correlation with the noise power spectral density of square-wave recordings for several tape media. In addition, the measurement revealed that long wavelength components dominate the MP tape head-medium noise, resulting in a decrease of the playback broadband noise voltage power for recordings with shorter wavelength. The measurement technique provides new insight into the head-medium interface spatial characteristics.