Giant magnetic anisotropy at the nanoscale: Overcoming the superparamagnetic limit



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Hernando Grande, Antonio and Crespo del Arco, Patricia and Garcia, M. A. and Fernández Pinel, E. and De la Venta,1, J and Fernández, A. and Penadés, S. (2006) Giant magnetic anisotropy at the nanoscale: Overcoming the superparamagnetic limit. Physical review B, 74 (5). ISSN 1098-0121

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It has been observed for palladium and gold nanoparticles that the magnetic moment at a constant applied field does not change with temperature over the range comprised between 5 and 300 K. These samples, with sizes smaller than 2.5 nm, exhibit remanent magnetization up to room temperature. The existence of permanent magnetism up to so high temperatures has been explained as due to the blocking of a local magnetic moment by giant magnetic anisotropies. In this Brief Report we show, by analyzing the anisotropy of thiol capped gold films, that the orbital momentum induced at the surface conduction electrons is crucial to understand the observed giant anisotropy. The orbital motion is driven by a localized charge and/or spin through spin- orbit interaction, which reaches extremely high values at the surfaces. The induced orbital moment gives rise to an effective field of the order of 10(3) T that is responsible for the giant anisotropy.

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©2006 The American Physical Society.
This work has been partially supported by the projects No. NAN2004-09125- C07-05 Spanish Ministry of Education and Science and No. 200560F0174 Spanish Council for Scientific Research.

Uncontrolled Keywords:Nanoparticles
Subjects:Sciences > Physics > Materials
Sciences > Physics > Solid state physics
ID Code:41800
Deposited On:14 Mar 2017 12:00
Last Modified:14 Mar 2017 12:00

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