Fabrication of Fully-Epitaxial Co$_{{{2}}}$MnSi/Ag/Co$_{{{2}}}$MnSi Giant Magnetoresistive Devices by Elevated Temperature Deposition

(001)-oriented epitaxial Co
₂
MnSi (CMS) films were grown by elevating the substrate temperature during deposition instead of a conventional post-annealing process. The CMS film deposited at 250°C showed a very flat surface morphology, large saturation magnetization, and a highly L2
₁
-ordered crystal structure. A CMS/Ag/CMS giant-magnetoresistive device with CMS layers grown at 250°C showed the high magnetoresistance ratio (33%) at room temperature. This ratio was close to that realized in the case of samples fabricated using post-annealing at 500-550°C. The elevated temperature deposition for the Heusler electrodes is a promising method to fabricate a practical magnetic read sensor for next generation hard disc drives without high temperature annealing process over 300°C.