Fabrication and Characterization of Fully Epitaxial Magnetic Tunnel Junction Field Sensors Using a ${\rm Co}_{2}{\rm MnSi}$ Thin Film

Fully epitaxial magnetic tunnel junctions (MTJs) consisting of a Co₂MnSi (CMS) upper free layer, a MgO tunnel barrier, and a Co₅₀Fe₅₀ lower pinned layer were fabricated for sensor application. The fabricated MTJs exhibited clear exchange-biased tunnel magnetoresistance (TMR) characteristics with a relatively high TMR ratios of 94% at room temperature (209% at 4.2 K) with V_half of approximately - 0.52 and + 0.54 V. Almost hysteresis-free TMR characteristics with sensitivity of approximately 0.4%/Oe were obtained with a cross magnetization configuration, in which the magnetization of the CMS free layer was oriented perpendicularly to that of the pinned layer.