Spin-cluster effects in the spin glass Fe2− x Ti1+ x O5 as observed by transverse-field muon-spin relaxation (abstract)

Transverse-field muon-spin-relaxation (μSR) experiments on the anisotropic spin glass Fe2−xTe1+xO5 were performed near and below the spin-glass temperature (x=0.25; Tg=43.5 K). Earlier1 single-crystal work has indicated that spin-cluster effects are present in zero field slightly above the glass temperature. The effect of a transverse-field (B⊥) upon the spin-glass transition and state has been studied by measuring the temperature dependencies of the muon hyperfine parameters at B⊥=5 kOe, and the field dependencies at 7, 17, and 49 K. The B⊥ direction has been chosen to be perpendicular to the c axis. Spin-cluster effects, as signaled by anomalous muon-spin relaxation, have been observed above 44 K in 5 kOe transverse field; further, exponential muon-spin relaxation above 60 K is observed as expected for a paramagnet. A substantial difference in the field dependence of the relaxation rate is seen between 49 K data and data taken at temperatures (7 and 17 K) well below Tg. A shift in Tg due to an applied magnetic field (⊥ c axis) has not been observed. These single-crystal μSR results will be compared with earlier μSR work on metallic spin glasses, where in polycrystalline samples no spin-cluster effects have been observed.2