Fig. 1. The in-phase ac-susceptibility (χ′) vs. temperature (T) plots for Ir- and Ru-doped CeFe₂ alloys (from Ref. [9]).

Fig. 2. Magnetization (M) vs. temperature (T) plots for Ce(Fe_0.96Ru_0.04)₂ alloy (from Ref. [13]).

Fig. 3. Resistivity ratio vs. temperature (T) plots for Ce(Fe_0.96Ru_0.04)₂ alloy (from Ref. [13]).

Fig. 4. H–T phase diagram for Ce(Fe_0.96Ru_0.04)₂ alloy.

Fig. 5. Schematic representation of free energy for T* < T < T_N. The high-temperature state remains in a local minimum and is stable against infinitesimal energy fluctuations in this temperature regime. The height of the barrier between the minima corresponding to the high and low-temperature phases at T_N (curve a) decreases with decreasing T and then disappears at T* (curve d). Curves b and c represent the free energy at two intermediate temperatures between T_N and T* with Tb > Tc.

Fig. 6. Normalized magnetization of Ce(Fe_0.96Ru_0.04)₂ (M/M₀) measured as function of time (t) at various fixed temperatures along the FCC path. The solid lines represent the fits using the KWW exponential function. The inset shows the characteristic relaxation time τ obtained from the fitting using the KWW function as a function of T (from Ref. [69]).

Fig. 8. Magnetization of PSMO measured during warming from 5 K in a magnetic field of 20 kOe. The three curves, as labeled, correspond to the sample being cooled from 300 K in fields of 30, 20 and 10 kOe. In two cases (30 and 10 kOe), the field is changed to 20 kOe isothermally at 5 K. The cooling history dependence is striking (from Ref. [35]).

Fig. 9. Two polymorphic modifications of Gd₅Ge₄: (a) the Sm₅Ge₄-type, which supports either the paramagnetic or antiferromagnetic states; and (b) the Gd₅Si₄-type, which the system adopts when it orders ferromagnetically. Both are layered structures built from nearly identical slabs (one of the slabs is marked by a bracket in (a)) and are related to one another by shear displacements of the neighboring slabs in the directions shown by short arrows near each of the slabs. The numbers above the arrows indicate the magnitude of the displacements. The most drastic difference is observed in the interslab Ge–Ge interactions, with corresponding interatomic distances that vary from 3.62 to 2.62 Å, as marked (from Ref. [24]).

Fig. 10. Magnetization of Al-doped PCMO measured while warming from 5 K in a magnetic field of 40 kOe. The three curves, as labeled, correspond to the sample being cooled from 300 K to the lowest temperature in fields of 60, 40 and 30 kOe. In two cases (60 and 30 kOe), the field is changed to 40 kOe isothermally at 5 K. The cooling history dependence is striking (from Ref. [35]).

Fig. 7. Resistivity and magnetization of Nd_0.5Sr_0.5MnO₃ as functions of magnetic field (from Ref. [28]).