Giant tunneling magnetoresistance in fully epitaxial body-centered-cubic Co/MgO/Fe magnetic tunnel junctions

Abstract

Fully epitaxial bcc Fe1-x Cox (001) MgO (001) Fe (001) magnetic tunnel junctions (x=0, 0.5, 1) were fabricated with molecular-beam epitaxy and microfabrication techniques. While the bcc Fe(001) and Fe0.5 Co0.5 (001) electrodes had similar magnetoresistance (MR) ratios of about 180% at room temperature, the bcc Co(001) electrode exhibited a higher MR ratio up to 271% at room temperature (353% at 20 K). The fact that the MR ratio for a bcc Co electrode is much higher than that for a bcc Fe electrode is consistent with first-principle calculations, indicating the importance of electrode band structure in the k∥ =0 direction. © 2005 American Institute of Physics.