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We present bulk and neutron scattering measurements performed on the isotopically enriched $^{154}\mathrm{Sm_2Ti_2O_7}$ and $^{154}\mathrm{Sm_2Sn_2O_7}$ samples. Both compounds display sharp heat capacity anomalies, at 350 mK and 440 mK, respectively. Inelastic neutron scattering measurements are employed to determine the crystalline electric field (CEF) level scheme, which includes transitions between the ground-state and first excited $J$ multiplets of the $\mathrm{Sm}^{3+}$ ion. To further validate those results, the single-ion magnetic susceptibility of the compounds is calculated and compared with the experimental DC-susceptibility measured in low applied magnetic fields. It is demonstrated that the inclusion of intermultiplet transitions in the CEF analysis is fundamental to the understanding of the intermediate and, more importantly, low temperature magnetic behaviour of the Sm-based pyrochlores. Finally, the heat capacity anomaly is shown to correspond to the onset of an all-in-all-out long-range order in the stannate sample, while in the titanate a dipolar long-range order can be only indirectly inferred., 13 pages, 10 Figures

A tight connection of scattering to thermodynamic models is missing for clay systems. A new approach called "locally columnar model" gives an attempt for making this connection. The scattering model assumes an up-lining of clay particles with strong paracrystalline order and refers to a chemical potential/distance dependence. The thermodynamic model assumes a bidisperse distance distribution and gives input to the scattering model. Experimentally, polymer/clay systems with many molecular polymer masses were studied showing all very similar scattering curves. While the dominating bulk phase shows only the same weak tendency to stack formation for all molecular polymer masses, one coexisting phase with stronger stack formation was identified. The latter sample was used to determine the thickness of the clay platelets with adsorbed polymer that was then used to model the dominating bulk phase. The comparisons to the theory revealed that (a) most polymers are tightly bound to the clay, and (b) an agreement between the modeling and the theory was achieved. The main result of the experiments is the fraction of free polymers of 1:2400 that are not tightly bound to the clay particles.

We report an extensive study on the zero field ground state of a powder sample of the pyrochlore ${\mathrm{Yb}}_{2}{\mathrm{Ti}}_{2}{\mathrm{O}}_{7}$. A sharp heat capacity anomaly that labels a low temperature phase transition in this material is observed at 280 mK. Neutron diffraction shows that a quasicollinear ferromagnetic order develops below ${T}_{\mathrm{c}}$ with a magnetic moment of $0.87(2){\ensuremath{\mu}}_{\mathrm{B}}$. High resolution inelastic neutron scattering measurements show, below the phase transition temperature, sharp gapped low-lying magnetic excitations coexisting with a remnant quasielastic contribution likely associated with persistent spin fluctuations. Moreover, a broad inelastic continuum of excitations at $\ensuremath{\sim}0.6$ meV is observed from the lowest measured temperature up to at least 2.5 K. At 10 K, the continuum has vanished and a broad quasielastic conventional paramagnetic scattering takes place at the observed energy range. Finally, we show that the exchange parameters obtained within the framework of linear spin-wave theory do not accurately describe the observed zero field inelastic neutron scattering data.