Enhancement of exchange field in CoFe/IrMn by Os/Cu buffer layer.

Enhancement of exchange field (H_ex) and thermal stability of the textured CoFe/IrMn with Os/Cu buffer layer and Os diffusion barrier layer were studied. As revealed by x-ray Diffraction (XRD), an Os (0002) surface mesh was observed to form on Cu (100)/Si (100). The growth of CoFe (111)/IrMn (111) on such a template is parallel to the Os (0002). With the Os/Cu buffer layer, the CoFe/IrMn presents an enhancement of 70 Oe on H_ex larger than that without Os/Cu. The H_ex of the textured sample was 230 Oe at room temperature and it was increased to 330 Oe after 250 °C annealing. When the temperature reached 350 °C, H_ex vanished. The increment of the temperature at which the textured and the nontextured sample obtaining their maximum H_ex and the vanishing temperature of H_ex were 50 and 75 °C, respectively. Furthermore, the CoFe/Os (d)/IrMn slowed down the H_ex degradation. The sample with d=0.3 nm obtained its maximum H_ex at 250 °C and vanished when it reached 400 °C. The combination of CoFe/IrMn with Os/Cu buffer layer and Os barrier layer made the H_ex higher and also better thermal stability. [ABSTRACT FROM AUTHOR]