Promising electronic structure of double perovskite Sr₂TiMoO₆: Spin-polarized DFT+U approach

Abstract

Abstract:The electronic structure of double perovskite Sr 2 TiMoO 6 have been systematically investigated using first principle. The spin-polarized electronic band structure and the density of states reveal that the spin-up channel has metal behavior while the spin-down channel expresses semiconductor behavior with direct band gap of 2.92 eV. For valence band, the O-2p states is the mainly contributor for both spin-up and spin-down channels above -5.3eV. Between -7.7eV to -5.3eV, valence band is formed by O-2p states with admixture of Mo-4d states. For conduction band, from range 4 eV to 7.4 eV is mostly formed by Sr-3d. On the other hand, O-2p, Mo-4d as well as Ti-3d states mainly consists of the conduction band near Fermi energy, so those states need to be more concerned. The spin splitting may lead to unusual thermoelectric transport properties. IntroductionDouble perovskites A 2 BBÓ 6 (where A respects alkali earth metal or rare-earth element, B and B' are transition elements with electronic configuration in d-orbital) has double unit cell of normal perovskite. Numerous structure types and extensively useful properties have been widely investigated by using different elements on A, B or B´ sites. Double perovskites materials are exploited in a variety of physical properties such as half metallic [1], optoelectronic [2,3] magnetocaloric [4,5], antiferromagnetic [6], ferromagnetic [7], making their widely used in spintronic and optoelectronic devices [8,9]. In addition, double perovskites have been attracted attentions for thermoelectric performance due to good durability and low synthesis cost [10][11][12][13]. Because of high electronic conductivity and low thermal conductivity, double perovskite Sr 2 TiMoO 6 exhibits as promising thermoelectric material [14,15]. The absence of the electronic structure of double perovskite Sr 2 TiMoO 6 makes it is necessary to predict theoretically. We systematically studied the electronic structure of double perovskite Sr 2 TiMoO 6 based on the framework of density functional theory (DFT). The computational methods and details are presented as follows.

Investigation of structural and electronic properties of double perovskites A2LnRuO6 (A = Ba, Ca; Ln = Eu, Dy)

“…The change in the tolerance factor of double perovskite leads to a change in the structural arrangement. When there is an increment in the value of tolerance factor from 0.78 to 1.05, monoclinic/orthorhombic, tetragonal, and cubic structure double perovskite modifies to hexagonal crystal structure [46,47]. The value t ∼1 corresponds to cubic structure and for monoclinic structure t is less than one.…”