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 /1/, /2/. 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 either under the influence of lower temperatures or as a function of the angle between the easy axis of the magnetization and the external field. In Y2Co7microparticles the variation of the shape of the magnetization loop with decreasing temperature reveals a striking proof for a nucleation-determined reversal process. This behaviour is supported by the variation of the experimentally observed jump fields for different orientation angles which can be fitted to a Kondorsky-type function.