ISSN:
1089-7550
Quelle:
AIP Digital Archive
Thema:
Physik
Notizen:
Neutron-spin-echo (NSE) experiments were performed on polycrystalline samples of EuxSr1−xS for x=0.4 and 0.54 in the temperature range of 1.2〈T〈10 K and for 0.036〈Q〈0.18 A(ring)−1. The x=0.4 sample exhibits a paramagnetic (PM) to spin-glass (SG) transition near Tg ∼2 K. In the x=0.54 sample, large ferromagnetic correlations develop below 5 K and a SG state appears at lower temperatures. In the NSE experiment, the spin-spin correlation function S(Q,t) is measured directly for times between 0.03〈t〈5 nsec. At low temperatures, both materials exhibit a weak Q dependence in the dynamics and the spins are essentially frozen over the time range explored. On heating the x=0.4 sample, the spins start to fluctuate more rapidly, but no dramatic change occurs around Tg. On heating the x=0.54 sample, S(Q,t) decreases rapidly with time. Near 5 K, S(Q,t) is exponential (e−Γt) with Γ being strongly Q dependent. Measurements of the depolarization of the scattered beam confirms the absence of true long-range ferromagnetic order below Tc.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1063/1.335034
