From soft to hard magnetic Fe-Co-B by spontaneous strain: a combined first principles and thin film study
2015 (English)In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 27, no 47, 476002Article in journal (Refereed) PublishedText
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.
Place, publisher, year, edition, pages
2015. Vol. 27, no 47, 476002
Fe-Co, rare-earth free permanent magnet, magnetocrystalline anisotropy, tetragonal strain, DFT
IdentifiersURN: urn:nbn:se:uu:diva-270417DOI: 10.1088/0953-8984/27/47/476002ISI: 000365346800013PubMedID: 26548574OAI: oai:DiVA.org:uu-270417DiVA: diva2:895727
FunderSwedish National Infrastructure for Computing (SNIC), SNIC 001/12-198