An oscillating sample anisotropy meter

A dynamic instrument for determination of magnetocrystalline anisotropy energy has been developed. The sample is forced to oscillate with a fixed frequency and amplitude in a homogeneous applied magnetic field. The phase and the amplitude of oscillation for the perpendicular component of the magnetization vector, which determines the anisotropy energy, is detected in a suitable pick-up coil arrangement. The sample oscillation is obtained through an electrostatic excitation of a resonance mode in a high Q mechanical oscillation unit. The sensitivity of the instrument corresponds to the signal from a permanent magnet of moment 3*10 -6 emu (3.8*10 -15 V s m). This is equivalent in magnitude to the signal from a 1 mm spherical sample, which has a 0.02 Oe anisotropy field, exposed to minimum applied field (4 pi /3)M s .