Magnetic properties of polycrystalline Co2Cr1-xFexAlCo2Cr1-xFexAl alloys

We have investigated the magnetic properties of the Heusler phase Co2Cr1-xFexAlCo2Cr1-xFexAl in the composition regime (x=0.3-0.5)(x=0.3-0.5) in the disordered B2 phase. Both bulk and surface static and dynamic magnetic aspects were addressed by employing alternating gradient magnetometry (AGM), magneto-optical Kerr effect (MOKE) and Brillouin light scattering (BLS). All samples show ferromagnetic hysteresis loops and a tendency of increasing saturation magnetization MsMs with the iron content. With BLS the behavior of bulk spin waves and the Damon Eshbach (DE) surface spin wave mode have been studied. The spectra are typical for opaque bulk ferromagnetic samples with strong exchange. The measured spin wave frequencies as a function of magnetic field are in good agreement with the calculated values. Saturation magnetization and gyromagnetic ratio g have been determined from the field-dependent peak positions of the bulk and the DE modes. The gg-factor extracted from the DE mode shows a clear tendency of increase with increasing Fe-content. However, we could not find any peculiarities of the alloy with x=0.4x=0.4, which had been proposed as a Heusler phase on the basis of electronic structure calculations [T. Block, C. Felser, G. Jakob, J. Ensling, B. Muhling, P. Gutlich, R.J. Cava, J. Solid State Chem. 176 (2003) 646].