Surface morphology, resistivity, and magnetoresistance of Co, Fe, Ni, Co-Fe, and Ni-Fe nanoparticles on TiN layers induced by hydrogen plasma treatment

This paper studied the surface morphology characteristics, electrical resistivity, and magnetoresistance of cobalt, iron, nickel, cobalt-iron, and nickel-iron nanoparticles on a titanium nitride layer nucleated under hydrogen plasma treatment. Experimental results indicated that the grain size increases with the plasma treatment time. The optimum grain agglomeration into nanoparticles was observed after 10 min of plasma treatment. The correlation between resistivity and grain size was determined, wherein the resistivity decreased because of the larger grain sizes formed by nucleation and grain agglomeration after hydrogen plasma treatment. Substantially high magnetoresistance was achieved in the Ni-80 at.%Fe nanoparticles, which was approximately 9 times higher than that of the Ni-50 at.%Fe nanoparticles. This phenomenon was mainly due to the increased content of iron nanoparticles in the said alloy. However, increasing the plasma nucleation time to 60 min decreased the particle magnetoresistance by 150%.