Thickness effect on stress-induced exchange anisotropy of NiFe/NiFeMn

Samples with the structure Mo (20 nm)/NiFe (t nm)/NiFeMn (12 nm)/Mo (2 nm) were grown on the Al2O3 (11-20) substrates by a MBE system. Although no magnetic field was applied during depositions, shifted hysteresis loops were observed in as-deposited samples, which were attributable to the stress-induced exchange anisotropy. With increasing thickness of NiFe, the residual stress on NiFe decreased, which resulted in the decrease of NiFe anisotropy. The exchange field decreased with increasing NiFe thickness but with a transition point at t=12nm, at which the residual stress on top of NiFe might be significantly released. (C) 2000 American Institute of Physics. [S0021-8979(00)34308-0].