Temperature dependent resistance of exchange biased spin valves with extremely thin IrMn

Abstract

The properties of IrMn spin valves with IrMn layer thicknesses ranging from 4 Å to 28 Å are explored at temperatures to 5 K. In particular, the temperature dependence of the resistance is investigated. The structure of the spin valves is: Si/50 Å Ti/40 Å NiFe/8 Å Co/30 Å Cu/30 Å Co/tIrMn/50 Å Ti. The low temperature GMR is not greatly affected by the thickness of the IrMn. The thinner the IrMn, the lower the temperature at which the GMR is adversely affected. This is consistent with a reduction in the blocking temperature. A number of interesting features in the coercivity and field training are IrMn thickness dependent. The exchange field, coercive field, GMR and resistance each show characteristic temperatures. All of these and the blocking temperature depend on tIrMn. Because the temperature dependence of the magnetic fields in these samples is so complicated we examine the directly measured resistance as a function of temperature.