We present in this paper the structural and magnetic properties of high aspect ratio Co nanoparticles (~10) at high temperatures (up to 623 K) using in situ X ray diffraction (XRD) and SQUID characterizations. We show that the anisotropic shapes, the structural and texture properties are preserved up to 500 K. The coercivity can be modelled by u0Hc=2(Kmc+Kshape)/Ms with Kmc the magnetocrystalline anisotropy constant, Kshape the shape anisotropy constant and Ms the saturation magnetization. Hc decreases linearly when the temperature is increased due to the loss of the Co magnetocrystalline anisotropy contribution. At 500K, 50% of the room temperature coercivity is preserved corresponding to the shape anisotropy contribution only. We show that the coercivity drop is reversible in the range 300 - 500 K in good agreement with the absence of particle alteration. Above 525 K, the magnetic properties are irreversibly altered either by sintering or by oxidation.
@article{arxiv.1208.4403,
title = {High temperature structural and magnetic properties of cobalt nanowires},
author = {Kahina Ait Atmane and Fatih Zighem and Yaghoub Soumare and Mona Ibrahim and Rym Boubekri and Thomas Maurer and Jérémie Margueritat and Jean-Yves Piquemal and Frédéric Ott and Grégory Chaboussant and Frédéric Schoenstein and Noureddine Jouini and Guillaume Viau},
journal= {arXiv preprint arXiv:1208.4403},
year = {2014}
}
Comments
8 pages, 7 figures, submitted to Journal of Solid State Chemistry