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ATOMIC ORDERING AND MAGNETIC PROPERTIES IN Nd50Fe40Al10 GLASSY HARD MAGNETS

N. Lupu1,2,* , H. Chiriac1, J. M. Greneche3, A. Inoue2

Affiliation

  1. National Institute of Research and Development for Technical Physics, Iasi, Romania
  2. Institute for Materials Research, Tohoku University, Sendai, Japan
  3. Laboratoire de Physique de L’État Condensé, UMR CNRS 6087, Université du Maine, Le Mans, France

Abstract

Structures with atomic medium-range order (MRO) of 2-4 nm are observed in the Nd50Fe40Al10 “amorphous” melt-spun ribbons by high resolution transmission electron microscopy (HRTEM). The volume fraction and size of the MRO regions increases as the cooling rate decreases, leading to the increase of the coercive field from 80 kA/m to about 350 kA/m when the ribbon thickness increases from 25 to 120 mm. The huge increase of the coercive field up to 4 MA/m as temperature decreases below room temperature in the maximum applied field of 7.2 MA/m is ascribed to the competition between exchange interactions and local anisotropies. The role of the MRO regions as pinning centers is discussed..

Keywords

Coercivity-thickness dependence, High-coercivity glassy alloys, Magnetic clusters, Medium-range ordered structures.

Submitted at: April 26, 2004
Accepted at: June 10, 2004

Citation

N. Lupu, H. Chiriac, J. M. Greneche, A. Inoue, ATOMIC ORDERING AND MAGNETIC PROPERTIES IN Nd50Fe40Al10 GLASSY HARD MAGNETS, Journal of Optoelectronics and Advanced Materials Vol. 6, Iss. 2, pp. 615-618 (2004)