Control of ferromagnetism is of critical importance for a variety of proposed spintronic and topological quantum technologies. Inducing long-range ferromagnetic order in ultrathin 2D crystals will provide more functional possibility to combine their unique electronic, optical and mechanical properties to develop new multifunctional coupled applications. Recently discovered intrinsic 2D ferromagnetic crystals such as Cr₂Ge₂Te₆, CrI₃ and Fe₃GeTe₂ are intrinsically ferromagnetic only below room temperature, mostly far below room temperature (Curie temperature, ~20–207 K). Here we develop a scalable method to prepare freestanding non-van der Waals ultrathin 2D crystals down to mono- and few unit cells (UC) and report unexpected strong, intrinsic, ambient-air-robust, room-temperature ferromagnetism with T_C up to ~367 K in freestanding non-van der Waals 2D CrTe crystals. Freestanding 2D CrTe crystals show comparable or better ferromagnetic properties to widely-used Fe, Co, Ni and BaFe₁₂O₁₉, promising as new platforms for room-temperature intrinsically-ferromagnetic 2D crystals and integrated 2D devices.

The magnetocaloric effect and refrigeration capacity (RC) of ${\text{Gd}}_{55}{\text{Co}}_{20}{\text{Al}}_{25}$ and ${\text{Gd}}_{55}{\text{Ni}}_{25}{\text{Al}}_{20}$ bulk metallic glasses (BMGs) have been investigated. Large magnetic entropy changes $\Delta S_M$ of 11.2 and $10.8\text{J}{\text{kg}}^{-1}{\text{K}}^{-1}$ and large RC values of 846 and $920\text{J}{\text{kg}}^{-1}$ are obtained for ${\text{Gd}}_{55}{\text{Co}}_{20}{\text{Al}}_{25}$ and ${\text{Gd}}_{55}{\text{Ni}}_{25}{\text{Al}}_{20}$ , respectively, at a field change of 7 T. The RC value ($640\text{J}{\text{kg}}^{-1}$ at 5 T or $920\text{J}{\text{kg}}^{-1}$ at 7 T) of ${\text{Gd}}_{55}{\text{Ni}}_{25}{\text{Al}}_{20}$ BMG is larger than that reported for all magnetocaloric materials, including crystalline and amorphous materials measured under the same conditions. The large RC value is due to the broad $\Delta S_M$ peak (more than 100 K), which is caused by the disordered structure of an amorphous material. The large $\Delta S_M$ and RC values make these Gd-based ternary BMGs attractive candidates for magnetic refrigeration applications.

The magnetic phase transitions and the magnetocaloric effect in the Ising antiferromagnet DySb have been studied. A field-induced sign change of the magnetocaloric effect has been observed which is related to a first-order field-induced metamagnetic transition from the antiferromagnetic to the ferromagnetic states at/below the Néel temperature TN, while the negative field-induced entropy change is found to be associated with the first-order magnetic transition from the paramagnetic to the ferromagnetic states above TN. The large magnetic-entropy change (−20.6J∕kgK at 11K for a field change of 7T), together with small hysteresis, suggests that DySb could be a potential material for magnetic refrigeration in the low-temperature range.

Glass-forming ability, spin-glass (SG) behavior, and magnetocaloric effect in Gd₅₅Ni_xAl_45-x (x = 15, 20, 25, 30) metallic alloys were investigated. A ferromagnetic SG behavior was observed for glassy ribbons with compositions of x = 15, 20, and 25, but it disappeared for that of x = 30. Furthermore, the maximum magnetic entropy change (−ΔS_m^max) increased with the increasing Ni/Al-ratio while the decrease of full width at half −ΔS_m^max was almost negligible. Accordingly, −ΔS_m^max of 9.25 J kg⁻¹ K⁻¹, adiabatic temperature change of 4.3 K and refrigeration capacity of 851 J kg⁻¹ under 50 kOe were obtained for Gd₅₅Ni₃₀Al₁₅ glassy alloy.

Dislocation activity is critical to ductility and the mechanical strength of metals. Dislocations are the primary drivers of plastic deformation, and their interactions with each other and with other microstructural features such as grain boundaries (GBs) lead to strengthening of metals. In general, suppressing dislocation activity leads to brittleness of polycrystalline materials. Here, we find an intermetallic that can accommodate large plastic strain without the help of dislocations. For small grain sizes, the primary deformation mechanism is GB sliding, whereas for larger grain sizes the material deforms by direct amorphization along shear planes. The unusual deformation mechanisms lead to the absence of traditional Hall-Petch (HP) relation commonly observed in metals and to an extended regime of strength weakening with grain refinement, referred to as the inverse HP relation. The results are first predicted in simulations and then confirmed experimentally.