Materials Chemistry and Physics, Vol.186, 592-597, 2017
Spin-orbit coupling induced structural stability and semi-metallic state in La-3 Ir-3 O-11
La-3 Ir-3 O-11 crystallizes in a cubic symmetry with its structure composed of electronically active Ir06 octahedral motifs, which are corner and edge shared. Empirical considerations suggest Ir to be in the +4.33 valence state in La-3 Ir-3 O-11, thereby anticipating the material to be a good conductor primarily due to the presence of holes in the crystal field split t(2g) bands of the Ir 5d manifold. However, a comprehensive investigation of the electronic structure by means of first principles calculations find La3 Ira On to be a spin-orbit driven semi-metallic iridate, with its Fermi energy comprised of both hole and electron bands. The properties of the electron-hole asymmetry in La-3 Ir-3 O-11 is clearly manifested in the temperature dependent variation of electrical conductivity and Seebeck coefficient, which are calculated using the Boltzmann transport theory. Besides, finding that Fermi energy is positioned in a steep valley like feature in the density of states spectra, the calculations also predict that both hole and electron doping would induce a semi-metal to metal transition in La-3 Ir-3 O-11 (C) 2016 Elsevier B.V. All rights reserved.