Effects of nitrogen concentration variation in molybdenum nitride underlayer for spin valves

We have studied magnetic and thermal properties of MoN films with different nitrogen concentrations. When a small amount of nitrogen is incorporated into the Mo-underlayer of a top-type spin valve, we do not observe any significant thermal degradation of its magnetic properties after annealing at 220 deg. C. The magnetoresistance ratio of the as-deposited spin-valve structure is 7.0% and slightly increases to 7.5 % even at the annealing temperature of 220 deg. C. The amount of nitrogen in the MoN underlayer seems to affect the texture growth of NiFe (1 1 1) and to improve the magnetic characteristics of the spin valve. From the XPS analysis of MoN thin films and XRD analysis of NiFe films grown on the MoN underlayer, it is concluded that spin-valve structure grown on the MoN underlayer with N2 gas-flow rate of 5 sccm is more stable than that grown with N2 gas-flow rate of 1 sccm