Room-temperature ferromagnetism in ZnO-encapsulated 1.9 nm FePt3 nanoparticle-composite thin films with giant interfacial anisotropy.

Shen, Lei; Zhou, Tiejun; Wee, Rui Qi; Cher, Kiat Min; Ko, Hnin Yu Yu; Niu, Rui; Gong, Hao; Yuan, Zhimin et al. · Adv Mater · 2013

basic_science · Level V

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Abstract

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.