Using the Arrott–Noakes equation of state it is shown that the Curie point (TC) and the temperature where the magnetic entropy change is maximum (Tpeak) coincide only in the mean field approximation, but the Heisenberg model implies that Tpeak>TC even for homogeneous materials. The distance between Tpeak and TC increases with applied magnetic field following a power law. In both cases, TC corresponds to a singular point in the temperature dependence of the magnetic entropy change. The field dependence of the magnetic entropy change is exactly the same at the Curie temperature and at the temperature of the peak.

Liquid-vapor coexistence curves and critical parameters for hard-core 1:1 electrolyte models with diameter ratios $\lambda ={\sigma }_{-}/{\sigma }_{+}=1\mathrm{}$ to 5.7 have been studied by fine-discretization Monte Carlo methods. Normalizing via the length scale ${\sigma }_{\pm }=\frac{1}{2}({\sigma }_{+}+{\sigma }_{-})$, relevant for the low densities in question, both $T_c^{*}$ ( ${=k}_B{T}_c{\sigma }_{\pm }{/q}^2$) and ${\rho }_c^{*}$ ( $={\rho }_c{\sigma }_{\pm }^3$) decrease rapidly (from $\simeq 0.05$ to 0.03 and 0.08 to 0.04, respectively) as $\lambda$ increases. These trends, which unequivocally contradict current theories, are closely mirrored by results for tightly tethered dipolar dimers (with $T_c^{*}$ lower by $\sim 0\%–11\%$ and ${\rho }_c^{*}$ greater by $37\%–12\%$).

We propose a nonlocal interfacial model for 3D short-range wetting at planar and nonplanar walls. The model is characterized by a binding-potential functional depending only on the bulk Ornstein-Zernike correlation function, which arises from different classes of tubelike fluctuations that connect the interface and the substrate. The theory provides a physical explanation for the origin of the effective position-dependent stiffness and binding potential in approximate local theories and also obeys the necessary classical wedge covariance relationship between wetting and wedge filling. Renormalization group and computer simulation studies reveal the strong nonperturbative influence of nonlocality at critical wetting, throwing light on long-standing theoretical problems regarding the order of the phase transition.

The field dependence of the adiabatic temperature change $\Delta T_{\text{ad}}$ of second order phase transition materials is studied, both theoretically and experimentally. Using scaling laws, it is demonstrated that, at the Curie temperature, the field dependence of $\Delta T_{\text{ad}}$ is characterized by $H^{1/\Delta }$ . Therefore, as the magnetic entropy change $\Delta S_M$ follows a $H^{\left(1-\alpha \right)/\Delta }$ power law, these two dependencies coincide only in the case of a mean field model. A phenomenological construction of a universal curve for $\Delta T_{\text{ad}}$ is presented, and its theoretical justification is also given. This universal curve can be used to predict the response of materials in different conditions not available in the laboratory (extrapolations in field or temperature), for enhancing the resolution of the data and as a simple screening procedure for the characterization of materials.

We derive a non-local effective interfacial Hamiltonian model for short-ranged wetting phenomena using a Green's function method. The Hamiltonian is characterized by a binding potential functional and is accurate to exponentially small order in the radii of curvature of the interface and the bounding wall. The functional has an elegant diagrammatic representation in terms of planar graphs which represent different classes of tube-like fluctuations connecting the interface and wall. For the particular cases of planar, spherical and cylindrical interfacial (and wall) configurations, the binding potential functional can be evaluated exactly. More generally, the non-local functional naturally explains the origin of the effective position-dependent stiffness coefficient in the small-gradient limit.