Brian William Karr

Review of the Physics of Magnetoresistive Readers

The rapid increase in areal density storage capacity in magnetic hard disk drives over the past decade has, to a large extent, been enabled by advances in reader technologies. We will here review the underlying physics of spin valves and tunneling readers with an emphasis on the interplay between transport, magnetism, materials properties, and signal-to-noise. Finally, we will give a a brief outlook to some of the technologies currently under development for future readers.

FePt as Read Sensor Hard Bias Material

A low temperature chemical ordering approach was presented for L10 phase FePt alloys application in read sensor hard bias. We show that platinum seed and cap layers together can help the iron-rich FePt layer to achieve A1 to L10 phase transformation at temperatures as low as 300 °C. For platinum-rich FePt alloy iron seed and cap layers are effective in promoting its phase transformation. Element cap and seed together are more effective to obtain high coercivity than either of them alone. In order to implement FePt permanent magnet in transducer product, new thermal processes and sequences are needed.