A magnetic and Mössbauer spectral study of the spin reorientation in NdFe11Ti and NdFe11TiH.

The ac susceptibilities of NdFe₁₁Ti and NdFe₁₁TiH, both of which crystallize with the I4/mmm tetragonal ThMn₁₂-type structure, have been measured between 20 and 300 K and the results reveal spin reorientations at ∼185 K and at 100±1 K, respectively. The Mössbauer spectra of NdFe₁₁Ti and NdFe₁₁TiH have also been measured between 4.2 and 295 K and fits of the observed line shape profiles indicate that the spin-reorientations in both compounds correspond to a rotation from an axial orientation to a canted or basal orientation upon cooling. Both the low temperature canted or basal magnetic structures and the lowering of the spin-reorientation temperature upon hydrogenation result from the competing neodymium and iron magnetic anisotropies and differing relative second-, fourth-, and sixth-order contributions as a function of temperature and hydrogen content of the neodymium to the magnetic anisotropy energy. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]