We studied what effect exchange bias had on magnetic noise under high-temperature or low-aspect-ratio conditions. We found that a steep increase in magnetic noise started at around 150°C with a low exchange bias (Jk∼0.4 erg/cm2), and attributed this to the decrease in exchange bias. We measured the dependence of magnetic noise with a high exchange bias (Jk∼1.0 erg/cm2) on temperature and found that magnetic noise was reduced under high-temperature conditions (∼250°C). We also found that magnetic noise could be diminished at room temperature even for a TMR head with a low aspect ratio (∼0.5). This indicates that the pinned layer instability increased by reducing the head size was improved with a high exchange bias.
