MAGNETIZATION REVERSAL IN Y-CO PERMANENT-MAGNET PARTICLES OBSERVED BY THE VIBRATING REED MAGNETOMETER

The vibrating reed magnetometer (VRM) is a very sensitive tool for the investigation of magnetization processes in small particles of permanent magnet materials. Using a modified version of this apparatus information about the magnetization reversal in uniaxially anisotropic Y-Co compounds is obtained from the magnetization jump fields in microscopic particles. In Y//2Co//7 microparticles the variation of the shape of the magnetization loop with decreasing temperature reveals a striking proof for a nucleation-determined reversal process. This behavior is supported by the variation of the experimentally observed jump fields for different orientation angles which can be fitted to a Kondorsky-type function.