Dependence of the magnetic and magnetoelastic properties of (TbFe2)1−xBx melt-spun alloys on x

Abstract

Rare earth–iron alloys containing highly anisotropic rare earth ions exhibit huge values of magnetostriction in the crystalline compounds with large values still maintained in the amorphous counterparts (for amorphous (TbFe2)87B13 λs was found to be 620 ppm at 77 K and 1.6 T). Melt-spun ribbons have a high potential for applications due to their softer magnetic properties and dimensions (∼25 μm thick) allowing lower applied fields and higher operating frequencies. Melt-spun ribbons of TbFe2 containing between 3 and 14 at. % boron as the glass former were prepared and exhibit an x-ray amorphous structure for x⩾7 at. % B. Their magnetic and magnetostrictive properties are discussed in terms of the boron concentration. For the amorphous alloys little variations in these properties are observed whereas for x<7 at. % significant changes take place due to a nanocrystalline structure. By applying a two-sublattice mean-field model to the M(T) data, the intrasublattice and intersublattice exchange parameters have been obtained and are compared with previous results on crystalline TbFe2. The results are consistent with the differences in Curie temperatures.