Quantum description of ferromagnet metal nanoparticles

The quantum physics of normal metal nanoparticles can be understood simply by recognizing the discreteness of individual electron eigenenergies and th e dominant role played by Coulomb interactions in determining the rate at w hich the chemical potential increases with electron number. Ferromagnetic m etal nanoparticles, on the other hand, have collective magnetization degree s of freedom that are responsible for additional low energy excitations. We discuss some issues that arise in attempting to achieve a unified and cons istent quantum description of both collective and quasiparticle physics in magnetic metal nanoparticles, especially when acknowledging the essential r ole of spin-orbit coupling and the magnetic anisotropy it produces. (C) 200 1 Elsevier Science Ltd, All rights reserved.