P9

Magneto-optical investigations and ion beam-induced modification of materials with high spin polarization (Hamrle / Hillebrands)

During the second period, we will investigate newly developed Heusler compounds in thin film form, such as Co₂MnSi, CoMnGe, Co₂Fe_xMn_1-xSi, Co₂Fe_xAl_1-xSi, Co₂FeAl_1-xSi_x, and Co₂MnSi_1-xAl_x in addition to the established and studied systems Co₂FeSi and Co₂Cr_0.6Fe_0.4Al, using linear and quadratic magneto-optical Kerr effect magnetometry and Brillouin light scattering spectroscopy. Of central focus will be the investigation of the magnetic properties at the structural phase transitions. We further propose to address the modification of these materials by using ion irradiation because this technique has the capability of potentially improving the magnetic and half-metallic properties. Such experiments are especially interesting near the structural phase transitions.

Samples for analysis and irradiation will be received from Projects P 2 (Jakob), P 4 (Tremel), P 11 (Jourdan), and P 12 (Ando). The irradiated samples will be structurally characterized by X-ray diffractometry in Project P 11 (Jourdan) while the chemical analysis will be carried out by scanning electron microscope in P 7 (Felser/Schönhense). Measurements of the spin polarization properties of irradiated samples will be performed within Project P 10 (Cinchetti/Aeschlimann). The interdependence of magnetic anisotropy and spin-orbit coupling will be investigated in collaboration with Project P 5 (Elmers), where XMCD measurements on irradiated samples will be performed. A similar investigation of the interdependence between anisotropy and magnetoresistive properties will be carried out in collaboration with Project P 2 (Jakob).