Magnetisation of isolated single crystalline Fe-nanoparticles measured by a ballistic Hall micro-magnetometer
We present here the first magnetisation measurements on isolated single crystalline Fe-nanoparticles performed with a ballistic Hall micro-magnetometer. The measurements have a sensitivity of \(\) and thus provide us the possibility to study the mechanisms of magnetisation reversal in a single nanoparticle. The magnetic properties of the nanoparticles are influenced by their crystal structure and shape, and the presence of an oxide surface layer. They exhibit curling of the magnetic moments, but also a novel hysteresis behaviour. The spin configurations found for the system agree well with numerical calculations based on a Heisenberg Hamiltonian including the exchange and dipole interaction and surface anisotropy.
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