Investigation of Thermal Demagnetization Effects in Data Recorded on Advanced Barium Ferrite Recording Media

Abstract

The thermal stability of data prerecorded onto advanced barium ferrite recording media has been studied. This type of media has been demonstrated to have excellent recording performance for ultranarrow read widths and at high linear densities. However, the reduction in size of the particles used in this type of media, compared with conventional metal particle media, could potentially affect its archival storage capability due to thermal demagnetization effects. The thermal stability of the media has been studied by making time-dependent coercivity measurements, using a standard vibrating sample magnetometer. From these measurements, a value of K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">u</sub> V/k <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> T ap 100 was obtained, indicating acceptable archival thermal stability. To determine if data recorded in this media is in fact thermally stable, tapes were also prewritten with pseudorandom encoded data patterns at various linear densities. The tapes were then baked, at temperatures up to 59 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">deg</sup> C and for times up to 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> seconds. The data was read back after each bake cycle using a nominally 1.0-mum read width giant magnetoresistive read head. No significant degradation in the quality of the read-back data was found, even after several baking cycles at increasing temperatures. This indicates that this media type does indeed have good archival thermal stability. It has also been found that the fundamental recording performance of this media is very acceptable for narrow read widths and at linear densities up to at least 360 kbpi.