The distribution and fluctuation rate of the internal magnetic field were determined in samples of ${\mathrm{Cd}}_{1\mathrm{-}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$Te (0.27≤x≤0.65) by measurements of the relaxation rate and precession frequency of implanted positive muons in longitudinal and transverse applied fields. The results show a critical-like divergence of the ${\mu }^{+}$ spin relaxation on approaching the spin-glass transition temperature $T_g$, with a critical exponent that scales with x. Relaxation rates and frequency shifts are consistent with the presence of a large hyperfine component in the ${\mu }^{+}$ spin interaction due to superexchange. The spin dynamics is dominated by fluctuations at all temperatures. Interesting effects were also observed in the temperature range 60<T<250 K which cannot be described fully by trapping or detrapping processes and which remain a puzzling feature of the results.

• Received 26 January 1988

DOI:https://doi.org/10.1103/PhysRevB.38.1183