TDPAC calculations for mixed SDW and Zeeman hyperfine interactions

The time differential perturbed angular correlation curves have been calculated for the hyperfine field distribution arising from the superposition of an isotropic system of spin density waves and of an external magnetic field. The results of these calculations have been applied to the Cr-Ta system. The agreement between the experiments and the calculations is fair. This shows that the spin density waves of chromium are not significantly polarized by a 12 kOe magnetic field. However a large negative shift of the Zeeman interaction is observed in the liquid nitrogen experiment: ΔH/H = -0.18 +- 0.02. The negative sign of the shift shows that the hyperfine field is antiparallel to the local magnetization. (Auth.)