Co$_2$FeSi Based Magnetic Tunnel Junctions With BaO Barrier

Abstract

BaO has been introduced as a novel tunnel barrier material in magnetic tunnel junctions (MTJs). Due to the good agreement regarding lattice constants and crystal structure, we believe BaO to be particularly suitable as barrier in MTJs containing Heusler compound electrodes. Co <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> FeSi/BaO/Fe MTJs have been fabricated by molecular beam epitaxy (MBE) and investigated in terms of microstructure, transport properties and tunnel magneto resistance (TMR). A TMR amplitude as high as 104% at room temperature (RT) has been achieved for very small bias voltages ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Bias</sub> ) and a strong dependence on <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Bias</sub> could be observed as the TMR ratio decreases with increasing <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Bias</sub> to about 14% at <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Bias</sub> = 10 mV.