Self-consistent screening of a positive muon in a spin-polarized electron gas

The electron spin-density distribution around a positive muon has been calculated self-consistently for a range of metallic densities using the spin-density functional formalism. The enhancement of the spin density at the μ⁺ site over the ambient polarization is found to be considerably smaller than the corresponding charge-density enhancement. The results are used to estimate the hyperfine field at interstitial positive-muon sites in ferromagnetic Fe, Co, Ni, and Gd. Comparison is made with the most-recent experimental data.