Local magnetic moment formation at ~(119)Sn Mossbauer impurity in RFe_2 (R = rare - earth metals) Laves phases compounds

摘要

The purpose of the present work is to theoretically study the local magnetic moment formation and the systematics of the magnetic hyperfine fields at a non-magnetic s-p Mossbauer ~(119)Sn impurity diluted on R sites (R = rare - earth metals) of the cubic Laves phases intermetallic compounds RFe_2. One considers that the magnetic hyperfine field has two contributions (i) the contribution from R ions, calculated via an extended Daniel-Friedel U- Phys. Chem. Solids 24 (1963) 1601] model and (ii) the contribution from the induced magnetic moments arising from the Fe neighboring sites. We have in this case a two-center Blandin-Campbell-like [Phys. Rev. Lett. 31 (1973) 51; J. Magn. Magn. Mater. 1 (1975) 1 ] problem, where a magnetic 3d-element located at a distance from the ~(119)Sn impurity gives an extra magnetization to a polarized electron gas which is strongly charge perturbed at the ~(119)Sn impurity site. We also include in the model, the nearest-neighbor perturbation due to the translational invariance breaking introduced by the impurity. Our self-consistent total magnetic hyperfine field calculations are in a very good agreement with recent experimental data.