Fabrication of Metastable Solid Solution in Rare Earth-Transition Metal Alloys, and Their Magentic Properties

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Gd-Fe, Gd-B, C and (Gd, Tb-Fe)_<80>Si_<12>B_8 metastable solid solutions were prepared by rapidly quenching from melts. X-ray analysis, electron microscope observation, magnetic measurements, and Mossbauer spectroscopy were carried out to make clear the structure and magnetism of rare earth metal- transition metal metastable solid solutions.1. Gd_xFe_<1-x>X-ray structural analysis revealed that, while the hcp solid solution is formed at X<greater than or equal>0.7, the amorphous state is at 0.2<less than or equal>X<less than or equal>0.6. Both the amorphous alloy and hcp solid solution are ferrimagnet. Curie temperature Tc of the solid solution (X<greater than or equal>0.7) increases with an decrease of X, and becomes close to Tc of the amorphous state (0.2<les2. Gd_<chi>B_<1-chi>While the substitutional solid solution is formed at X<greater than or equal>0.8, the amorphous state is at X<0.8. The lattice constant C decreases with a decrease of X in the solid solution. The solid solutio … More n is a ferromagnet, whose Curie timperature Tc is close to Tc of hcpGd. The amorphous state is also ferromagnet, whose Curie temperature Tc is lower than that of hcpGd because of a random s3. (Gd_<chi>Fe_<1-x>)_<80>Si_<12>B_8The amorphous phase is formed at 0.7<less than or equal>X<less than or equal>1.0. Exchange interactions J between Gd magnetic moments are considered to distribute widely from negative to positive because of a random structure and an oscillating RKKY interaction. This distribution of J causes an instability of ferromagnetism. Fe magnetic moments in (Gd_<1-x>Fe_x)_<80>Si_<12>B_8 strongly couple with neighboring near Gd magnetic moments, make Gd-Gd interactions positive and stabilize a ferromagnetism. Mossbauer spectroscopy showed that an internal magnetic field is about 100kOe at X=0.7, indicating an apparent decrease of magnetic moment from 2.2mu_B for alphaFe to about 1.0mu_B for X=0.7. In (Tb_<chi>Fe_<1-x>)_<80>Si_<12>B_8, the amorphous phase is formed in 0.7<less than or equal>X<less than or equal>1.0. The amorphous alloys show a spin-glass like behavior giant local magnetic anisotropy of Tb atoms. Less