Large Magnetoresistance Effect in Epitaxial Co2Fe0.4Mn0.6Si/Ag/Co2Fe0.4Mn0.6Si Devices

Fully epitaxial current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) devices with a Co2Fe0.4Mn0.6Si/Ag/Co2Fe0.4Mn0.6Si structure were fabricated. The bottom and top Co2Fe0.4Mn0.6Si layers had good crystallinity and an L2(1)-ordered structure. In addition, we found from scanning transmission electron microscopy (STEM) measurements that both Co2Fe0.4Mn0.6Si/Ag and Ag/Co2Fe0.4Mn0.6Si interfaces were very flat and sharp. The magnetoresistance (MR) ratio at room temperature was 74.8%, the largest to date for CPP-GMR devices. CPP-GMR devices with Co2Fe0.4Mn0.6Si electrodes would be very useful for the next generation of hard disk drive (HDD) read heads. (C) 2011 The Japan Society of Applied Physics