Exchange bias in ordered antiferromagnets by rapid thermal anneal without magnetic field

Exchange bias of bottom-pinned bilayers and tunnel junctions (TJs) containing MnPt as the antiferromagnet was set by rapid thermal annealing. An annealing duration of 1 min was sufficient to induce the structural phase transition to obtain antiferromagnetic behaviour in MnPt without cool down in a magnetic field. For Mn51.5Pt48.5 (20 nm)/Co90Fe10 (5 nm) bilayers the exchange coupling was found to be (J(ex) = 0.4 erg cm(-2)). Higher rapid thermal annealing temperatures led to increased diffusion in the layers reducing the pinned layer magnetic moment. Structural characterization by x-ray diffraction and transmission electron microscopy clearly showed the phase transition in the MnPt: film. Exchange bias, coercive and free layer coupling field of a rapid thermal annealed and a standard annealed TJ were compared.