Positive muons in antimony bismuth alloys

Stroboscopic μSR and TD-μSR techniques were used to measure the μ+ Knight shift Ksub(μ) and relaxation rate Λ in SbBi alloys as functions of magnetic field H, temperature T, the angle theta between H and the crystalline c axis, and the concentration [Bi] of alloyed Bi. In pure Sb and in SbBi (6.5%), Ksub(μ)(theta = 0) and Ksub(μ)(theta = π/2) both decrease linearly with T up to about 100 K, but both Ksub(μ) and its anisotropy are smaller in the 6.5% alloy, indicating a 'dilution' effect. With 15 at.% Bi, Ksub(μ) is reduced further but its T-dependence and that of Λ are dramatically altered. At low temperatures Ksub(μ)(theta = 0) in SbBi(15%) actually becomes negative and the sign of the anisotropy is reversed. In the same sample, Λ is proportional to H at both 20 K and 150 K; at 120 K Λ is proportional to Ksub(μ) if theta is used as an implicit variable, but at 36 K this is not the case. A consistent phenomenological description is offered. (Auth.)