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Hysteresis loop measurements in rare-earth based permanent magnets: the role of applied field rate and sample geometry

C. BEATRICE1, O. BOTTAUSCIO1, F. FIORILLO1,* , E. PATROI2

Affiliation

  1. Istituto Nazionale di Ricerca Metrologica (INRIM), Torino, Italy
  2. ICPE-CA Advanced Research Institute for Electrical Engineering, Bucharest, Romania

Abstract

Methods currently employed in the characterization of hard magnets are briefly discussed and the challenges posed by the precise measurement of the hysteresis loop and its parameters in rare-earth based permanent magnets are stressed. It is shown that fast and reliable measurements can be performed using the Pulsed Field Magnetometer method, exploiting either the magnetometric or the fluxmetric approach. Full assessment of the obtained results calls for appraisal of the dynamic phenomena engendered by the fast changing applied field. Besides the ubiquitous magnetic aftereffect, eddy currents may lead to loop swelling in sintered rare-earth based samples. It is demonstrated that the role of eddy currents can be accounted for and the quasi-static hysteresis loop can be retrieved by simple analytical formulation..

Keywords

Permanent magnets, Magnetic measurements, Pulsed Field Magnetometer, Eddy currents, Magnetic aftereffect.

Submitted at: Jan. 25, 2007
Accepted at: April 15, 2007

Citation

C. BEATRICE, O. BOTTAUSCIO, F. FIORILLO, E. PATROI, Hysteresis loop measurements in rare-earth based permanent magnets: the role of applied field rate and sample geometry, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 4, pp. 1120-1126 (2007)