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

Abstract

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 degrees C annealing. When the temperature reached 350 degrees 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 degrees 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 degrees C and vanished when it reached 400 degrees 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. (c) 2007 American Institute of Physics.