Analysis of the irreversible field-cooled (FC) and the zero-field-cooled (ZFC) magnetic susceptibilities of one ferrimagnetic and three ferromagnetic systems, measured at different applied magnetic fields, shows that the irreversibility indicated by the difference between the FC and the ZFC susceptibilities arises from magnetic anisotropy. The two susceptibilities are related to each other through the coercivity which is a measure of the anisotropy. The ZFC susceptibility can be calculated from the FC susceptibility (or vice versa) and the coercivity.

The realm of high energy, large wave vector spin waves in ultrathin films and at surfaces is unexplored because a suitable method was not available up to now. We present experimental data for an 8 ML thick Co film deposited on Cu(001) which show that spin-polarized electron energy loss spectroscopy can be used to measure spin-wave dispersion curves of ultrathin ferromagnetic films up to the surface Brillouin zone boundary.

No abstract

The magnetic behaviour of at low magnetic fields has been studied by ac susceptibility, and field cooled (FC) and zero field cooled (ZFC) magnetization measurements. The cluster-glass-like magnetic behaviour of the compound is found to originate from its magnetocrystalline anisotropy as similar properties are observed for ferromagnetic systems also. The cluster glass freezing temperature and its magnetic field dependence, the irreversibility between the FC and ZFC magnetization curves, the shape of the low-field susceptibility curves, etc are related to the magnitude and temperature variation of the coercivity which is a measure of the anisotropy, and the ratio where is the applied magnetic field.

The role of thermal scattering in spin-dependent transport of hot electrons at 0.9 eV is studied using a spin-valve transistor with a soft Ni(80)Fe(20)/Au/Co base. Spin-dependent scattering makes the collected electron current depend sensitively on the magnetic state of the base. The magnetocurrent reaches 560% at 100 K, decays with increasing temperature, and a huge effect of 350% still remains at room temperature. The results demonstrate that thermal spin waves produce quasielastic spin-flip scattering of hot electrons, resulting in mixing of the two spin channels.