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The Hall effect is a useful probe of the magnetization in thin metallic films since the signal is inversely proportional to the film thickness. Previously, the minimum in the coercivity, derived from the Hall hysteresis loop as a function of the angle of the applied field, has been used to determine the hard axis of magnetic thin films. A vibrating sample magnetometer can be used in this fashion if coherent rotation is the magnetization reversal mechanism. However, we show that even in the case of the Stoner–Wohlfarth model, the minimum of the Hall coercivity does not coincide with the hard axis. We propose an alternative method for determining the easy axis, which is independent of the magnetization reversal mechanism and does not require measuring the entire hysteresis loop. In addition, since for an arbitrary orientation of the applied field the measured Hall voltage will contain components due to magnetoresistance as well as the Hall effect, it is possible to extract a measure of the in-plane and perpendicular magnetization. Using this information, we derive a method of producing vector plots that show the magnitude and direction of the magnetization as a function of applied field for various applied-field orientations. Examples using CoCr and TbFe will be presented.

Neutron scattering methods are employed to study the temperature and magnetic field dependence of the spin dynamics in the alloy Fe"Cr& " for x =0.34, 0.28, 0.26, 0.24, and 0.22. For x =0.34 and 0.28, the system orders ferromagnetically and exhibits well-defined spin waves throughout the ferromagnetic phase. For x~0.26, ferromagnetism is also present but at low temperatures a spin-glass-like phase exists. For these concentrations the spin-wave excitations are observed within the ferromagnetic phase but as the temperature is lowered towards the' spin-glass regime the spin-wave frequency decreases. At low temperatures, within the spin-glass regime, no well-defined excitations are present, but an intense quasielastic peak is observed.Application of a magnetic field causes a reemergence of the spin-wave excitations.

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