Structural, magnetic and magnetocaloric properties of double perovskite Ho2MMnO6 (M = Fe, Co, and Ni)

We report our systematic investigation of structural, magnetic, and magnetocaloric properties of double perovskite compounds Ho2FeMnO6, Ho2CoMnO6, and Ho2NiMnO6, which crystallize into monoclinic crystal structure with P21/n space group. The magnetic phase transition temperatures are determined to be 7.5 K for Ho2FeMnO6, 69 K for Ho2CoMnO6, and 71.5 K for Ho2NiMnO6, where Ho2FeMnO6 exhibits an antiferromagnetic to paramagnetic phase transition, while Ho2CoMnO6 and Ho2NiMnO6 exhibits ferromagnetic to paramagnetic phase transitions. The magnetic entropy change (−ΔSM), which are found to be 10.2, 3.4 and 4.7 J/kgK at ΔH = 7 T for Ho2FeMnO6, Ho2CoMnO6, and Ho2NiMnO6 samples, respectively. The magnetic and magnetocaloric characteristics of double perovskite compounds are well explained based on structural and electronic properties. For future applications, our quantitative method provides a guideline for magnetic property engineering of double perovskite systems containing ferromagnetic 3d transition metals.