Magnetic structure and magnetocaloric properties of SrGd2O4 prepared by solid-state method

The preparation of SrGd2O4 was carried out by the solid-state route and its structural, magnetic, magnetocaloric properties have been investigated. The compound formation was confirmed using X-ray diffraction analysis. The elaborated sample annealed at 1300 °C in the air for 24 h, crystallizes in the orthorhombic structure with Pnma space group. Combining different models, a detailed analysis of the magnetic phase transitions in the SrGd2O4 compound has been performed. At 2.8 K, the phase transition from the AFM (Anti-ferromagnetic) state to the PM (Para-magnetic) state is 2nd order. Furthermore, the magnetization process exhibits a large magnetocaloric effect (MCE). The maximum magnetic entropy change (–ΔSM) near 2.8 K and refrigerant capacity (RCP) are 20.39 J. Kg−1. K−1 and 163.12 J. Kg−1, respectively, for a field change of 0–5 T. With negligible thermal and field hysteresis, SrGd2O4 can be considered as a cryogenic refrigerant material. A phenomenological model is now used to comprehend the MCE behavior of this sample. The exponents δ (delta) is properly revealed to be nearby those of the tricritical M-F-M (Mean-Field-Model) value. This simply reflects the existence of an AFM long-range order in our sample.