Correlation of thermal stability and anisotropy distribution in data storage tapes prepared from ultrafine particles

The correlation between thermal stability and anisotropy field (H_A) distribution was studied for data storage tapes prepared from ultrafine metal particulate (MP) composition and Ba-ferrite particles. At low temperature, the thermal effect had no influence in either tape. H_A distributions in easy direction of both tapes were excellent at 77 K. The angular distribution of H_Awas sharp in the case of MP tape, whereas the easy axes were widely distributed in the case of Ba-ferrite tape. In the easy direction, a proportion of particles had low anisotropy values in both tapes at 350 K. The normalized magnetization decay of MP and Ba-ferrite tapes in a -0.5 kOe field at 350 K was 0.4 and 1.4%/decade, respectively, and the respective thermal stability factors were 81 and 49. The magnetization stability is essentially determined by the magnitude and angular distribution of H_A.