Anisotropy of W in Fe and Co

Abstract

The magnetization and magnetic anisotropy of iron-rich Fe-W and W-Co intermetallics and nanostructures are investigated by first-principle calculations. The W atom is antiferromagnetically coupled to nearest neighbor Co atom and interface Fe atom in the case of Fe-W multilayers. The first anisotropy constants are positive, nearly zero, or negative, depending on the atomic structures. Typical anisotropy energies per atom are -0.513 meV for a dilute W-Co alloy, -0.06 meV for W <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , and 0.44 meV for W <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Fe <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> (0.1 meV/atom ~1MJ/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ). These values are of interest for permanent-magnet applications but also indicate the need for careful structural control and for a more detailed investigation of structure-property relationships in Fe-W nanostructures.