Advanced Materials, Vol.25, No.11, 1639-1645, 2013
Room-Temperature Ferromagnetism in ZnO-Encapsulated 1.9 nm FePt3 Nanoparticle-Composite Thin Films with Giant Interfacial Anisotropy
As synthesized 1.9-nm FePt3 nanoparticles are superparamagnetic at room temperature. Coating those nanoparticles with ZnO renders them permanently ferromagnetic with coercivity field of 650 Oe at room temperature. First-principles calculations indicate that giant interfacial anisotropy, induced by the strong spin-orbit interaction of enhanced orbit momentum of Fe, overcomes the superparamagnetic limit, leading to exceptional room-temperature permanent ferromagnetism. The findings are important for the understanding of the origin of permanent ferromagnetism at ultrasmall size and critical for ultrahigh density recording and information processing.
Keywords:permanent (hard) ferromagnetism;spin-orbit interaction;giant interfacial anisotropy;superparamagnetic;FePt;ZnO