[en] In this work we study the formation of the local magnetic moments and the related magnetic hyperfine fields at a Ta impurity diluted on the R site of the RCo₂ intermetallic hosts (R= rare-earth elements). In order to calculate the local magnetic moment at a Ta impurity diluted in these intermetallics, we use a two band model, including the nearest-neighbor perturbation due to the translational invariance breaking introduced by the impurity. The calculated total hyperfine fields are in good agreement with the available experimental data

[en] Published in summary form only

[en] Published in summary form only

[en] We present a theoretical description of the local magnetic moment and hyperfine field of diluted s-p, noble and transition metal nd impurities (n=3,4,5) in Co host. The cases of s-p and noble impurities (Cu, Ag, Au) are described within an extension of the Daniel and Friedel model. The case of nd impurities is described within the classical picture of Wolff-Clogston. The calculated hyperfine fields for all the impurities are in excellent agreement with the observed experimental data

[en] In this work we study the magnetic hyperfine fields at nd (n=3, 4, 5) transition impurities diluted in ferromagnetic Gd and Tb hosts. The nd impurities are described within the Wolff-Clogston picture and the next-neighbor perturbation, due to the translational invariance breaking introduced by the impurity is also included in this work. The calculated hyperfine fields are in good agreement with the observed experimental data

[en] Published in summary form only

[en] In this work we study, at finite temperature, the systematics of the local magnetic moments and the related magnetic hyperfine fields on a Ta impurity embedded in XFe₂ Laves phase compounds (X=Y or Gd). We use a two-coupled sublattice Hubbard Hamiltonian, where the d-d electronic interactions are treated adopting a functional integral approach. The calculated magnetic hyperfine fields as a function of temperature are in good agreement with the available experimental data

[en] This paper reports on an experimental investigation of fine structure changing collisions between cold and trapped ⁸⁵Rb atoms. Our previous work [Eur. Phys. J. D 7, 317 (1999)] reported on our assessment of the contribution of FSC to the total trap loss using photoionization by a cw laser to detect the atomic fragments in the 5P_1/2 state originating from these collisions. The Doppler effect plays an important role in the detection scheme and had a limiting effect on our previous experiment. To overcome this problem, we have used a pulsed laser in this work. The signal/noise ratio was improved, allowing us to measure the intensity and frequency dependence of the loss rate due to FSC. A comparison of our results with the semiclassic Gallagher-Pritchard model revealed some disagreements, for which we propose several arguments to attempt to explain these discrepancies. We believe that these results should stimulate theoretical work on this field. (orig.)

[en] Published in summary form only

[en] Published in summary form only