Exchange bias in NiMn-based magnetic films after laser thermal annealing

This paper deals with the exchange bias in Ni81Fe19(15 nm)/Ni45Mn55(x nm) bilayers annealed by laser. The influences of the laser parameters on the exchange bias (Hex) were systematic investigated. The results show that the Hex was strongly affected by the energy density of laser, and that there exists a threshold of energy density (about 150 mJ/cm2) where the exchange bias appears. With the increase of energy density, the exchange coupling becomes stronger and reaches a maximum; then it disappears gradually. In the case of the thickness of NiMn was 25 nm, the Hex was 26.2 kA/m after laser thermal annealing, which was slightly higher than that of conventional thermal annealing (22.3 kA/m).