Observation of Griffiths phase and giant magnetocaloric effect in double perovskite oxide RE ₂ FeCrO ₆ (RE = Gd, Tb, Dy, Er)

Abstract The magnetic properties of double perovskite oxide RE 2 FeCrO 6 (RE = GD, Tb, Dy, Er) were systematically studied, and the Griffiths phase evolution was observed. In Tb 2 FeCrO 6 , Dy 2 FeCrO 6 , and Er 2 FeCrO 6 , there are antiferromagnetic (AFM)‐ferromagnetic (FM) first‐order phase transition and the Griffiths phase with coexistence of FM and paramagnetic (PM) was observed by the EPR spectra. Gd 2 FeCrO 6 has an AFM–PM second‐order phase transition, and there is no first‐order phase transition in the range of ∆ H = 0–50 kOe. As the temperature decreases, all four sets of samples present χ −1 ( T ) deviates downwards from the Curie–Weiss linear behavior from 0.2 to 5 kOe, corresponding to the typical characteristics of Griffiths phase evolution. In addition, all four sets of samples have excellent magnetocaloric performance. Especially, the Gd 2 FeCrO 6 oxide has giant magnetic entropy change and relative cooling power (−∆ S M max = 30.31 J/kg K and RCP = 312.8 J/kg when ∆ H = 50 kOe). From the perspective of low‐temperature magnetic refrigeration application, the present work provides important candidate references for magnetic component researchers.