Impact of nitrogen impurities on the tungsten properties for application in spintronic

Abstract

We report the impact of the tungsten crystal structure on the spin transport properties of permalloy/tungsten bilayers grown by sputtering on (100) silicon. The microstructure of the tungsten layer was modified using a reactive N 2 /argon mixture during the fabrication process. The analysis combines ferromagnetic resonance and inverse spin Hall effect (ISHE) experiments. A correlation with the electrical and structural characterization indicates that an initial β -W stabilization notably improves the measured ISHE signal. Nevertheless a subsequent increment of the N 2 pressure degrades the signal, probably due to higher interstitial nitrogen and degradation of the interface quality. The interplay between the resistivity and disorder gives an optimal growth condition to enhance the tungsten spin current sensing property.