4 Reports on Experimental Results 4.17 All-optical characterization of the spintronic Heusler material

In the last years, the class of cobalt-based full Heusler compounds was subject to intensive research efforts related to the Þelds of spintronics and magnon spintronics [13]. Related studies range from basic research including ab-initio calculations and the fabrication of novel materials to application-oriented scenarios in the Þeld of information technology utilizing the advantages given by this class of materials. The huge interest in the cobalt-based Heusler compounds is mainly based on the half-metallic character of at least some of the possible compositions. This half-metallicity is a result of the different character of the minority- and majority-spin electrons. While the majority-spin electrons exhibit a metallic band structure with Þnite density of states at the Fermi level, the minority-spin electrons have a semi-conductor-like nature with a band gap at the Fermi level. As a result of this band structure, many cobalt-based Heusler compounds exhibit a remarkably high spin polarization compared to conventional 3d-ferromagnets and compounds. The high spin polarization and the high Curie temperature of the compounds make them promising candidates for spintronic appli-cations in data storage or sensing devices. Another consequence of the half-metallicity is the low Gilbert damping of some of the compounds [4, 11, 19]. A low Gilbert damping opens the perspec