Gradually Devitrified Co-Based Metallic Glass As a Model Material for Testing Néel's Theory of the Rayleigh Rule

H.K. Lachowicza,b, F. Popławskia,b, S.N. Kanea, M. Kuźmińskia, and T. Kulikc a Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warszawa, Poland, b College of Science, Al. Lotników 32/46, 02-668 Warszawa, Poland, c Department of Materials Science & Engineering, Warsaw University of Technology, Narbutta 85, 02-524 Warszawa, Poland

Received: November 11, 1998; in final form December 23, 1998

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It is shown in the present paper that gradually devitrified Co-based non-magnetostrictive metallic glass is an excellent model material to verify Louis Néel's theory of the Rayleigh rule. In the course of the calculations, Néel showed that the parameter p=bHca (where Hc is the coercivity, a and b are the coefficients of a quadratic polynomial expressing the Rayleigh rule) is expected to range between 0.6 (hard magnets) and 1.6 (soft). However, the experimental values of this parameter, reported in the literature for a number of mono- and poly-crystalline magnets, are much greater than those expected from the theory presented by Néel (in some cases even by two orders of magnitude). The measurements, performed for a series of Co-based metallic glass samples annealed at gradually increasing temperature to produce nanocrystalline structures with differentiated density and size of the crystallites, have shown that the calculated values of the parameter p fall within the range expected from Néel theory.

DOI: 10.12693/APhysPolA.95.287 PACS numbers: 75.50.Kj, 75.60.Ej