Manipulation of electronic structure via alteration of local orbital environment in [(SrIrO3)m, (SrTiO3)] (m=1, 2 and \infty) superlattices

Abstract

We investigated the electronic structure of [(SrIrO3)m, (SrTiO3)] (m = 1, 2, and ∞) superlattice (SL) thin films with optical spectroscopy and first-principles calculations. Our optical results confirmed the existence of the Jeff = 1/2 states in SL samples, similar to the bulk Ruddlesden– Popper series Srn+1IrnO3n+1 iridates. Apart from this similarity, in the SL samples we observed redshifts of the characteristic optical excitations in the Jeff = 1/2 state and an enhancement of the low-energy spectral weight, which implies a reduction in the effective electron correlation for bands near the Fermi energy. The DFT+U calculations suggested that the SrTiO3 layer intervened between SrIrO3 layers in the SLs activated additional hopping channels between the Ir ions, thus increasing the bandwidth and reducing the effective strength of the correlations. This work demonstrates that fabrication of iridium-based heterostructures can be used to finely tune electronic structures via alteration of their local orbital environments. © 2016 American Physical Society