Key Words:Magnetic domains;Edge dislocations - Iron oxides - Magnetic anisotropy - Magnetic materials - Magnetite;Contrast experiment - Hard magnetic property - Perpendicular magnetic anisotropy - Perpendicular magnetic recording - Soft magnetic nanomaterials - Soft magnetics - Strong anisotropy - Two-dimensional arrays

Abstract:In this study, abnormal hard-magnetic domains were discovered in Fe<inf>3</inf>O<inf>4</inf>@C composite material, in which well-ordered 16-nm-sized Fe<inf>3</inf>O<inf>4</inf>cubes were tightly embedded into carbon sheets of tens of nanometers thick. It was found that ca. 40 columns of Fe<inf>3</inf>O<inf>4</inf>nanocubes magnetically self-assembled into a single strip-type domain with perpendicular magnetic anisotropy. More strikingly, remarkable domain misalignments, which were very similar to common edge dislocations among atomic planes in crystal lattices, were clearly observed and termed as "domain dislocation" in this work. The hard-magnetic properties of Fe<inf>3</inf>O<inf>4</inf>@C material, including large coercivity of 2150 Oe, high M<inf>R</inf>/M<inf>S</inf>value of 0.9, and strong anisotropy energy of 3.772 × 10⁵erg/cm³, were further ascertained by carefully designed electromagnetic absorption contrast experiments. It is anticipated that the discovery of hard-magnetic domains and domain dislocations within 2-D arrays of soft-magnetic nanomaterials will shed new light on the development of high-density perpendicular magnetic recording industry.<br/> © 2015 AIP Publishing LLC.

Volume:118

Issue:7

Translation or Not:no