Giant muon knight shifts in antimony and antimony alloys

The Knight shift K_μ at the positive muon has been measured as a function of magnetic field, temperature, crystal orientation and alloyed impurity (bismuth or tin) in antimony. The anomalously large and anisotropic K_μ in pure Sb at low temperature has been confirmed and shown to be independent of magnetic field up to 9 kG; its anisotropic part is found to have the same strong temperature dependence as its isotropic component. The addition of 6.3 at.% Bi significantly reduces both K_μ and its anisotropy, but enhances their temperature dependence. The addition of 12.5 at.% Bi, or, more dramatically, as little as 0.3 at.% Sn to antimony is sufficient to reduce K_μ to a small value, effectively eliminating the anomalous behaviour.