# Magnetocaloric Properties and Critical Behaviour of the Sm\({}_{2}\)Ni\({}_{17}\) Compound
## 1 Introduction  
[PERSON] and [PERSON] achieved the first experimental demonstration of adiabatic demagnetization of paramagnetic salts, such as Gd\({}_{2}\)(SO\({}_{4}\))\({}_{3}\)-8H\({}_{2}\)O, reaching a temperature of 0.25 K [1], after the discovery of the magnetocaloric effect (MCE) by [PERSON] and [PERSON] [2] around the Curie temperature (\(T_{C}\)) of Ni. Later, [PERSON] et al. [3] reported the largest MCE for Fe\({}_{49}\)Rh\({}_{51}\). Subsequently, several promising materials, including Gd\({}_{5}\)(Ge,Si)\({}_{4}\)[4, 5, 6, 7], Fe\({}_{2}\)P [8, 9, 10, 11], and manganites R\({}_{1-x}\)A\({}_{x}\)MnO\({}_{3}\)[12, 13, 14, 15], have been extensively studied for their magnetocaloric properties around the ordering temperature (\(T_{C}\)). To this day, the investigation of magnetocaloric materials remains an area of interest for researchers. Recently, several studies have been published showing an interesting magnetocaloric effect over a range of operating temperatures [16, 17, 18].  
Rare earth (R) and transition metal (M) intermetallics have been thoroughly studied in recent years for their performance as permanent magnets, including R\({}_{2}\)Fe\({}_{17-x}\)M\({}^{\prime}\)\({}_{x}\) (M\({}^{\prime}\) = Al, Ga, Si) [19], RM\({}_{3}\)[20], R\({}_{5}\)M\({}_{19}\)[21], RM\({}_{11}\)M\({}^{\prime}\) (M = Ga, Ti, Co) [22], and recently for their magnetocaloric properties, e.g., La(Fe,Co,Si)\({}_{13}\)(H,C), R\({}_{2}\)Fe\({}_{17}\)[23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35].  
It has been shown that the R\({}_{2}\)Ni\({}_{17}\) systems (R = Gd, Tb, Dy, Ho, Er, Tm ) crystallize in the hexagonal Th\({}_{2}\)Ni\({}_{17}\) phase in the \(P6_{3}/mmc\) space group and are ferrimagnetic for atemperature lower than the Curie temperature (\(T_{C}\)), whereas the R = Y, Sm, and Lu compounds are ferromagnetic [36; 37; 38; 39]. Nevertheless, In contract to [PERSON] and Wallace [36], all Curie temperatures have been found to be lower than 200 K [36; 37; 38; 39].  
The R\({}_{2}\)M\({}_{17}\) intermetallic compounds have been identified as promising candidates for MCE compounds because of their ease of synthesis and their moderate price. For the binary R\({}_{2}\)M\({}_{17}\), the substitution of R and/or M has the potential to enhance the modest magnetocaloric effect that characterizes these systems [40; 41; 42].  
Recently, researchers have focused on the search for new magnetocaloric materials with good low-temperature performance, particularly those exhibiting second-order magnetic transitions (SOMT). SOMT materials are known to have a relatively high cooling capacity, although they typically do not have a very large magnetic entropy change (\(\Delta S_{\text{M}}\)). Other positive characteristics of SOMT materials include low magnetic hysteresis and an adjustable Curie temperature (\(T_{\text{C}}\)) by varying the composition [43; 44].  
In this work, we have studied the MCE of Sm\({}_{2}\)Ni\({}_{17}\) around \(T_{\text{C}}\). We have derived the MCE, the temperature-averaged entropy change (\(TEC\)), and the relative cooling power (\(RCP\)). Furthermore, we derived the critical exponent near \(T_{\text{C}}\) to determine the universality class of the studied compound.