title: From soft to hard magnetic Fe-Co-B by spontaneous strain: a combined first principles and thin film study.
abstract: In order to convert the well-known Fe-Co-B alloy from a soft to a hard magnet, we propose tetragonal strain by interstitial boron. Density functional theory reveals that when B atoms occupy octahedral interstitial sites, the bcc Fe-Co lattice is strained spontaneously. Such highly distorted Fe-Co is predicted to reach a strong magnetocrystalline anisotropy which may compete with shape anisotropy. To probe this theoretical suggestion experimentally, epitaxial films are examined. A spontaneous strain up to 5% lattice distortion is obtained for B content up to 4 at%, which leads to uniaxial anisotropy constants exceeding 0.5 MJ m(-3). However, a further addition of B results in a partial amorphisation, which degrades both anisotropy and magnetisation.
authors.affiliation: IFW Dresden, 01171 Dresden, Germany. Faculty of Mechanical Engineering, Institute of Materials Science, TU Dresden, 01062 Dresden, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Reichel
authors.forename: L
authors.initials: L
authors.lastname: Schultz
authors.forename: D
authors.initials: D
authors.lastname: Pohl
authors.forename: S
authors.initials: S
authors.lastname: Oswald
authors.forename: S
authors.initials: S
authors.lastname: Fähler
authors.forename: M
authors.initials: M
authors.lastname: Werwiński
authors.forename: A
authors.initials: A
authors.lastname: Edström
authors.forename: E K
authors.initials: EK
authors.lastname: Delczeg-Czirjak
authors.forename: J
authors.initials: J
authors.lastname: Rusz