Large exchange bias and high stability of CoFe/CrPt films with L10 CrPt as the pinning layer -: art. no. 092506

We have studied an antiferromagnetic L1(0) CrPt film as a pinning layer. dc magnetron sputtered [Pt/Cr] multilayers on a Co0.9Fe0.1 layer exhibit no exchange bias. After being annealed at 350 degrees C for 5 h in a vacuum, the equiatomic [Pt/Cr] multilayer stack is transformed into a uniform CrPt alloy film with L1(0) phase, which pins the adjacent 120 A CoFe layer with a pinning field of similar to 70 Oe and a coercivity of only 28 Oe. The hysteresis loop of this exchange biased system is almost square and the interdiffusion between the CrPt and the CoFe layers is rather small. The equivalent interface exchange energy Delta E, 0.12 erg/cm(2), is comparable to the typical value of FeMn biasing system. However, the blocking temperature, at which the exchange bias disappears, is as high as 600 degrees C, 150 degrees C higher than the highest value ever reported. Since it possesses extremely good thermal stability, large exchange bias, little interdiffusion, and high corrosion resistance, the antiferromagnetic CrPt film is proposed to serve as a pinning layer for magnetoresistive devices.