Formation of a nanobarrel structure in CPP-GMR spin-valve films

Abstract As a new approach for current-perpendicular-to-plane giant magnetoresistive (CPP-GMR) spin-valve films, we have proposed a new nanostructure to cause mesoscopic phenomena. For this purpose, we have successfully formed a nanobarrel structure composed of Cu granular-like shape surrounded by Al 2 O 3 insulator in which Cu nanoconducting channel punches through the Al 2 O 3 insulator both at the top and at the bottom. This nanobarrel structure was confirmed by high-resolution transmission electron microscope (HR-TEM) analysis. Both the resistance–voltage characteristics and the resistance–temperature characteristics showed the metallic conductance property, which is in good agreement with the nanostructure identified by HR-TEM analysis. The nanobarrel structure offers features compatible with both nano-ordered electron-confined structure by insulator and low resistance with metallic conductance.