Experimental magnetization-temperature curves for melt-spun ribbons of amorphous alloys (Dy0.33Fe0.67)1-xBx with x = 0, 0.05, 0.1 and 0.15 (in atomic fraction) are fitted with theoretical equations based on the mean field theory in order to investigate exchange couplings between constituent elements as a function of the B content. The sign of the exchange coupling between Dy and Fe is negative, indicating that the magnetization direction of Dy is antiparallel to that of Fe. The sign of the other two couplings are positive. The exchange coupling between Fe ions are greatest, while that between Dy ions is negligible. The exchange couplings between Fe ions, and between Dy and Fe increase with increasing B content, the increase of the latter being much greater than the former. Resultantly, the exchange coupling between Dy and Fe becomes about one half of that between Fe ions at the highest B content. The increase of the exchange coupling between Fe ions may be explained by the increase of the Fe-Fe separation with the increase of the B content. The total magnetization is dominated by the Dy sublattice magnetization. As the B content increases, the magnetization decreases over the whole temperature range, and the Curie temperature also decreases.
Bibliographical noteFunding Information:
SHL thanks Research Center for Advanced Magnetic Materials (an ERC at Chungnam National University) for its financial support of this work. The authors express their thanks to Dr. K.S. Kim at Chungbuk National University who helped to measure the M – T curves.
- Amorphous alloys
- B effects
- Exchange interactions
- Mean field theory
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics