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AM: Magnetismus

AM 2: Magnetische Phasenüberg
änge, Elektronentheorie

AM 2.2: Talk

Monday, March 26, 2001, 10:30–10:45, S 5.4

MAGNETIC AND STRUCTURAL PROPERTIES OF Nd₆₀Fe_30−xAl₁₀Co_x METASTABLE ALLOYS — •Patrica Crespo¹, Antonio Hernando¹, Golden Kumar², Shanker Ram², Stefan Roth³, Jürgen Eckert³, Karl-Hartmut Müller³, and Ludwig Schultz³ — ¹Instituto de Magnetismo Aplicado, P.O.Box 155 Las Rozas, 28230 Madrid, Spain — ²Materials Science Center, Indian Institute of Technology, Kharagpur, India — ³IFW Dresden, Institute for Metallic Materials, Dresden, Germany

Metastable Nd₆₀Fe_30−xAl₁₀Co_x alloys were prepared in the form of rods, 3 mm in diameter, by casting in a cold copper mold, and in ribbon shape, of about 20 to 30 mm thickness, by melt spinning. X-ray diffraction showed that the melt-spun ribbons were completely amorphous while in the case of the rods some crystallites can be resolved. At room temperature, the as-cast rods show a hard magnetic behavior with a coercive field of around 0.3 T, whereas the as-quenched ribbons were considerably softer with a coercivity lower than 0.03T. It is observed that after annealing some of the rods exhibit a field induced metamagnetic-like transition at room temperature and under an applied field of about 1T.

In addition, for the alloys in form of rods it is observed a drastic increase of the coercive field when the temperature is decreased, reaching a maximum value of around 2T at T=60K. Mössbauer spectroscopy has been performed in order to clarify the origin of such a hard magnetic behavior in nearly amorphous samples.