High-pressure synthesis, crystal structure, and properties of In _2NiMnO_6 with antiferromagnetic order and field-induced phase transition

摘要

In_2NiMnO_6, a new compound extending the family of double rare-earth perovskites R_2NiMnO_6 (R = rare earth, Y) to smaller R ions, was prepared using a high-pressure and high-temperature technique (6 GPa and 1600 K). Its crystal structure was investigated by synchrotron X-ray powder diffraction at room temperature: space group P2 _1 (No. 14, cell choice 2), Z = 2, a = 5.13520(1) ?, b = 5.33728(1) ?, c = 7.54559(4) ?, and β = 90.1343(1). A significant degree of ordering of Mn~(4+) and Ni~(2+) ions was observed. The dc and ac magnetization and specific heat measurements showed that In_2NiMnO_6 is an antiferromagnet with a Néel temperature T_N of 26 K. Its antiferromagnetism puts it apart from other members of the R_2NiMnO_6 family where a ferromagnetic ground state was observed, which is attributed to the superexchange interaction between Mn~(4+) and Ni~(2+) ions according to the Kanamori-Goodenough rules. A field-induced phase transition to a ferromagnetic state was observed from 18 kOe at 5 K, indicating that In_2NiMnO _6 is close to the antiferromagnetic-ferromagnetic transition boundary. First-principles calculations allowed us to explain its antiferromagnetism and the field-induced phase transition and predict the E* type antiferromagnetic ground state.