## 1 Introduction  
The pursuit of efficient cooling technologies has positioned cryogenic magnetic refrigeration as a promising field, with applications spanning from quantum computing and space exploration to advanced medical diagnostics [1]. This approach presents distinct advantages over traditional cooling methods, offering superior efficiency, reduced environmental impact, and capabilities to reach extremely low temperatures [2]. At its core, this technology exploits the magnetocaloric effect (MCE)--a phenomenon where magnetic materials undergo temperature changes when exposed to varying magnetic fields. During magnetization, the ordering of magnetic moments decreases magnetic entropy; during demagnetization, their randomization increases entropy and produces cooling [3]. For effective sub-Kelvin refrigeration, materials must demonstrate substantial magnetic entropy changes alongside minimal adiabatic temperature variations [4]. The development of such specialized magnetic refrigerants remains a central challenge in advancing this technology.  
In recent years, considerable efforts have been devoted to exploring novel magnetocaloric materials with enhanced performance in the ultra-low-temperature regime [5, 6]. Among the various material families, rare-earth-based compounds have emerged as promising candidates, owing to their large magnetic moments and diverse magnetic interactions [7, 8, 9, 10]. Gadolinium-based compounds have attracted significant interest due to the high magnetic moment of Gd\({}^{3+}\) ions (7.94 \(\mu_{B}\)) and their potential for achieving large MCE [11, 12, 13, 14, 15]. [PERSON] et al. reported on the GdF\({}_{3}\) compound, which features high spin,high-density structure, and weak ferromagnetic interactions [16]. This compound exhibits a maximum magnetic entropy change of up to 528 mJ\(\cdot\)cm\({}^{-3}\) K\({}^{-1}\) under a varying magnetic field of 0-9 T. [PERSON] et al. investigated the magnetism and magnetocaloric effect of the Gd\({}_{2}\)CuTiO\({}_{6}\) compound with a double perovskite structure [17]. Due to the exchange interactions between the Gd-4\(f\) and Cu-3\(d\) magnetic sublattices, this compound demonstrates enhanced low-temperature magnetocaloric effects, achieving a maximum magnetic entropy change of 51.4 J kg\({}^{-1}\) K\({}^{-1}\) under a magnetic field change of 0-7 T. [PERSON] et al. studied the magnetic properties and magnetocaloric effect of NaGd\({}_{9}\)(SiO\({}_{4}\))\({}_{6}\)O\({}_{2}\) single crystals [18]. The high magnetic density and relatively weak exchange interactions in this compound lead to a magnetic ordering transition at 2.6 K, with a volumetric magnetic entropy change of 382.8 mJ\(\cdot\)cm\({}^{-3}\) K\({}^{-1}\) under a magnetic field of 0-7 T. Therefore, gadolinium-based compounds with a high magnetic density are promising candidates for further exploration in the quest for high-performance cryogenic magnetic refrigerants.  
Frustrated magnetic systems, characterized by competing magnetic interactions that cannot be simultaneously satisfied, have been identified as a fertile ground for realizing low-temperature magnetocaloric materials [19; 20; 21; 22]. These frustrated magnetic configurations often exhibit enhanced MCE due to the presence of low-energy magnetic excitations [23]. In this work, we focus on the Gd\(\gamma\)(BO\({}_{3}\))(PO\({}_{4}\))\({}_{2}\)O\({}_{6}\) compound with monoclinic crystal, which combines a high density of Gd\({}^{3+}\) ions with a frustrated magnetic structure. The unique arrangement of Gd\({}^{3+}\) ions within the \(bc\)-plane and their stacking along the a-axis direction gives rise to competing magnetic interactions, making it an ideal platform for investigating low-temperature magnetocaloric effects. Through a comprehensive study of magnetic properties and MCE, we demonstrate the potential of Gd\(\gamma\)(BO\({}_{3}\))(PO\({}_{4}\))\({}_{2}\)O\({}_{6}\) as a promising cryogenic magnetic refrigerant.