Solid-state refrigeration technology based on caloric effects are promising to replace the currently used vapor compression cycles. However, their application is restricted due to limited performances of caloric materials. Here, we have identified colossal barocaloric effects (CBCEs) in a class of disordered solids called plastic crystals. The obtained entropy changes are about 380 J kg -1 K -1 in the representative neopentylglycol around room temperature. Inelastic neutron scattering reveals that the CBCEs in plastic crystals are attributed to the combination of the vast molecular orientational disorder, giant compressibility and high anharmonic lattice dynamics. Our study establishes the microscopic scenario for CBCEs in plastic crystals and paves a new route to the next-generation solid-state refrigeration technology.

The quest for materials hosting topologically protected skyrmionic spin textures continues to be fueled by the promise of novel devices. Although many materials have demonstrated the existence of such spin textures, major challenges remain to be addressed before devices based on magnetic skyrmions can be realized. For example, being able to create and manipulate skyrmionic spin textures at room temperature is of great importance for further technological applications because they can adapt to various external stimuli acting as information carriers in spintronic devices. Here, the first observation of skyrmionic magnetic bubbles with variable topological spin textures formed at room temperature in a frustrated kagome Fe Sn magnet with uniaxial magnetic anisotropy is reported. The magnetization dynamics are investigated using in situ Lorentz transmission electron microscopy, revealing that the transformation between different magnetic bubbles and domains is via the motion of Bloch lines driven by an applied external magnetic field. These results demonstrate that Fe Sn facilitates a unique magnetic control of topological spin textures at room temperature, making it a promising candidate for further skyrmion-based spintronic devices.

The magnetic transitions and magnetic and magnetostrictive properties of Tb x Dy 1−x ͑Fe 0.8 Co 0.2 ͒ 2 ͑0.20ഛ x ഛ 0.40͒ compounds have been investigated. The spin-reorientation temperature T SR decreases from above to below room temperature, when x is increased from 0.25 to 0.40. The easy magnetization direction at room temperature of the Laves phase lies along the ͗100͘ axis in compounds with 0.20ഛ x ഛ 0.27, while it lies along the ͗111͘ axis as 0.30ഛ x ഛ 0.40. The magnetocrystalline anisotropy constant K 1 at room temperature reaches a minimum value at x = 0.30, indicating it is near the composition for anisotropy compensation. The large polycrystalline saturation magnetostriction s Ϸ 980 ppm is observed for x = 0.30, which can be ascribed to the large magnetostriction coefficients 111 and 100 . 100 has a value larger than 600 ppm for the compounds with 0.30ഛ x ഛ 0.35, which can be attributed to the change of the filling of the 3d band due to Co substitution for Fe. Tb 0.30 Dy 0.70 ͑Fe 0.8 Co 0.2 ͒ 2 with a high magnetostriction and a low anisotropy is found to be a good candidate material for magnetostriction applications. A detailed spin configuration diagram for Tb x Dy 1−x ͑Fe 0.8 Co 0.2 ͒ 2 Laves phase around the composition for the anisotropy compensation is given, which should be a guide to develop novel magnetostrictive materials for applications in this series.

Electron-diffraction and high-resolution lattice images reveal superstructure stripes with wave vectors of (1/3, 0, 1/3) and (-1/3, 0, 1/3), which are associated with the ordered arrangement of F(-). Charge density distribution suggests that these stripes manifest themselves electronically as F(-)-Cr(3+)-F(-) zigzag chains, driven by the anisotropic charge interaction of F(-) anions.