(1) Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504 ULP-CNRS, B.P. 43, 67034 Strasbourg Cedex 2, France
Abstract:
We have studied the ultrafast magneto-optical response of CoPt3 ferromagnetic nanodots with diameters ranging from 0.2 to 1 μm. Our experiments combine an accurate temporal resolution using femtosecond laser pulses and a high spatial resolution ( 300 nm) obtained with a reflective confocal Kerr microscope. Our experimental approach allows exploring the dynamics of the magnetization of magnetic nanostructures over a broad temporal scale ranging from 100 fs to 1 ns. We report the corresponding relaxation behavior of the electrons and the spins initially excited with a large excess energy above the Fermi level.