A spinvalve using a permanent magnet as the pinned layer in a synthetic antiferromagnet of a spinvalve is described here. Permanent magnet materials can have the following advantages over antiferromagnetic materials: superior corrosion resistance, a large switching field even at relatively high temperatures, and not needing a high temperature anneal to set its magnetic orientation. The giant magnetoresistance, high field switching, and switching at high temperatures was investigated for various spinvalves using the following film stacks as the pinned layer: CoCrPt (CCP); CCPCoFe, CCPRuCoFe; and CCPCoFeRuCoFe. It was found that a thin CoFe layer between the CCP and Cu and between the CCP and Ru enhances giant magnetoresistance and antiferromagnetic coupling, respectively. When the CCP is used in a synthetic antiferromagnet, the CCP coercivity increases compared to a single layer of CCP. The switching field of CCP at 425℃ is >1000 Oe, at the same temperature the switching field for an antiferromagnetic material is ～0 Oe. If used in a magnetic readback head, the improved thermal stability may allow for larger bias currents and larger readback voltages.
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