Mott insulator behavior in the yttrium-based antimoniate oxide Ba2YSbO6

Abstract

Abstract A careful experimental and theoretical study of the double perovskite type material Ba2YSbO6 is reported. The results show that this yttrium-based antimoniate oxide crystallizes in a cubic structure, Fm 3 ¯ m (#225) space group, with evidence of the cationic ordering that characterizes a rocksalt superstructure, and tolerance factor slightly less than the unit (τ\u202f=\u202f0.9791) due to the size differences between the Y-O6 and Sb-O6 octahedrons. The magnetic response shows weak ferromagnetic effects for the temperature values studied (50, 200 and 300\u202fK), with evidence of an antiferromagnetic reentrance at T\u202f=\u202f118\u202fK under the application of low magnetic fields, which is attributed to the presence of polar ordering, accompanied by octahedral distortions caused by the movement of the cations Y3+ and Sb5+, whose effects are no longer observed in the presence of a fairly high external magnetic field (of the Tesla order). The results of the optical characterization by diffuse reflectance suggest the occurrence of a band gap Eg\u202f=\u202f4.61\u202feV, which is characteristic of an insulating material. The electronic structure calculations corroborate the insulating nature of the Ba2YSBO6 complex perovskite. The results allow classifying this material as a Mott insulator, in which the occurrence of intra-site spin-exchange facilitates unpaired spins to the 4d-t2g Yttrium states, mediated by the 2p Oxygen orbitals and 5p Antimony orbitals, resulting in the ferromagnetic character of the insulating material.