Noise properties and microstructure of oriented CoCrTa/Cr media

Magnetic and noise properties of oriented CoCrTa/Cr media sputtered at temperatures from ambient to 250 °C were studied and correlated with microstructural data from HRSEM and HRTEM micrographs. Coercivity increases monotonically and loop squareness decreases with substrate temperature. Transition and uniform magnetization noise power are highest for media sputtered at 150 °C. Micrographs and noise powers show that the media sputtered at 150 °C is relatively highly exchange‐coupled. Media sputtered below 150 °C shows topographic isolation, and those sputtered above 150 °C exhibit increasing intergranular isolation of about 10 A and thus lower exchange. Coercivity varies linearly but exchange drops abruptly at high temperature. Other mechanisms besides exchange contribute to the coercivity variation.