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Rare earth (RE) based RE - TM - X (TM = transition metal elements; X = P - block elements) materials have received continuous attention due to the exhibition of various intriguing magnetic functional characteristics. In this work, a combined experimental and theoretical investigation has been conducted in detail for RE Co 12 B 6 (RE = Ce, Pr, Nd) compounds with regard to their structural and magnetic properties, particularly the magnetocaloric effect and magnetic phase transition (MPT). All of the present RE Co 12 B 6 compounds are found to crystalize in the SrNi 12 B 6 -type structure and with a ferrimagnetic ground state, which is confirmed by density functional theory calculations and magnetization measurements. The magnetic moments of RE atoms and Co atoms tend to be in antiparallel alignment, and the MPT of these materials originates primarily from the spin-polarized 3 d electrons of the Co atoms, which can be greatly affected by the 4 f electrons of RE atoms. Considerable magnetocaloric effects have been observed around its own T C of 130, 157, and 160 K, for CeCo 12 B 6 , PrCo 12 B 6 , and NdCo 12 B 6 , respectively, which is related to a typical second-order MPT. The corresponding maximum magnetic entropy change and relative cooling power values,with field changes of 0–70 kOe, are determined to be 2.54, 2.84, and 2.77 J/kg K and 116.8, 156.2, and 155.1 J/kg, respectively. The MPT properties of present RE Co 12 B 6 compounds were studied in further detail by critical analysis using the modified Arrott Plot and Kouvel-Fisher methods, which can be explained within the frame of the 3D Heisenberg model with short-range magnetic interaction. [Display omitted] [ABSTRACT FROM AUTHOR]

• The quaternary RE Cr 2 Si 2 C (RE = Gd, Tb, Dy) compounds are fabricated. • The structural, magnetic, MTP and MC properties in RE Cr 2 Si 2 C were studied. • The GdCr 2 Si 2 C compound is considerable for cryogenic magnetic refrigeration. The rare earths (RE) based materials with large reversible magnetocaloric effects have been recently recognized as good candidates for practical cryogenic magnetic refrigeration. In this work, three RE -based quaternary silicon carbides of RE Cr 2 Si 2 C (RE = Gd, Tb, Dy) were synthesized and determined the crystal structure, magnetic properties, magnetic phase transition, and magnetocaloric performances. All RE Cr 2 Si 2 C compounds are crystallized in the carbon-filled CeMg 2 Si 2 -type crystal structure and revealed a second-order magnetic phase transition from ferromagnetic to paramagnetic without noticeable field or thermal hysteresis around the Curie temperatures (~10.9 K for GdCr 2 Si 2 C, ~16.6 K for TbCr 2 Si 2 C, and ~10.7 K for DyCr 2 Si 2 C). The magnetocaloric parameters including the maximum magnetic entropy change, temperature-averaged entropy changes with 3 K lift, as well as refrigerant capacity/relative cooling power are applied to determine the magnetocaloric performances, and the evaluated values are 21.7, 14.6 and 9.8 J/kgK, 20.97, 14.51, and 9.73 J/kgK, as well as 248.3/328.8, 302.8/393.8, and 211.3/274.9 J/kg for GdCr 2 Si 2 C, TbCr 2 Si 2 C, and DyCr 2 Si 2 C under the field change of 0–50 kOe. These results indicate that the GdCr 2 Si 2 C possesses promising magnetocaloric performances and is considerable for cryogenic magnetic refrigeration application. [ABSTRACT FROM AUTHOR]

• Three (Mn 0.5 Ni 0.5) 60+ x Ga 40- x skyrmion hosting alloys are fabricated. • Second order magnetic transition was confirmed. • Considerable MCE were observed in rare earth (RE)-free alloys. • Valuable clues for searching RE-free MCE materials. A systematic investigation of rare earth free magnets (Mn 0.5 Ni 0.5) 60+ x Ga 40- x (x = 3.3, 5.0, and 6.6) which are typical skyrmion hosting alloys are presented with respected to the crystal structure, magnetic phase transition and magneto-caloric effect (MCE). All the (Mn 0.5 Ni 0.5) 60+ x Ga 40- x alloys exhibit a hexagonal Ni 2 In-type structure with the P63/mmc space group confirmed by X-ray diffraction. The Mn and Ga/Ni atomic layers arrange alternately along the c -axis. The lattice parameters include a and c all as well as the Curie temperature (T C) all increase gradually with increasing Mn content. A second-ordered phase transitions from the state of ferromagnetic to paramagnetic has been determined around their own T C of 340, 348 and 351 K for (Mn 0.5 Ni 0.5) 63.3 Ga 36.7 , (Mn 0.5 Ni 0.5) 65 Ga 35 and (Mn 0.5 Ni 0.5) 66.6 Ga 33.4 , respectively. Moreover, the MCE performances of (Mn 0.5 Ni 0.5) 60+ x Ga 40- x alloys were determined by the figure merits of the maximum magnetic entropy change (-Δ S M max), temperature-averaged entropy change (TEC) with 5 K-lift and refrigerant capacity (RC). The values of -Δ S M max, TEC (5), and RC are 3.26 J/kg K, 3.24 J/kg K, and 229.9 J/kg for (Mn 0.5 Ni 0.5) 63.3 Ga 36.7 , 3.72 J/kg K, 3.70 J/kg K and 287.3 J/kg for (Mn 0.5 Ni 0.5) 65 Ga 35 , as well as 3.56 J/kg K, 3.53 J/kg K and 265.1 J/kg for (Mn 0.5 Ni 0.5) 66.6 Ga 33.4 under the external applied field change of 0–7 T, respectively. [ABSTRACT FROM AUTHOR]