Infrared Spectroscopic Evidences of Strong Electronic Correlations in (Sr1-xLax)3Ir2O7.

Gihyeon Ahn,S J Song,T Hogan,S J Moon,S D Wilson

doi:10.1038/srep32632

Gihyeon Ahn, S J Song + Show 3 more

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https://doi.org/10.1038/srep32632

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Abstract

We report on infrared spectroscopic studies of the electronic response of the (Sr1−xLax)3Ir2O7 system. Our experiments revealed hallmarks of strong electronic correlations in the evolution of the electronic response across the filling-controlled insulator-metal transition. We observed a collapse of the Jeff = 1/2 Mott gap accompanying the transfer of the spectral weight from the high-energy region to the gap region with electron doping. The intraband conductivity at the metallic side of the transition was found to consist of coherent Drude-like and incoherent responses. The sum rule and the extended Drude model analyses further indicated a large mass enhancement. Our results demonstrate a critical role of the electronic correlations in the charge dynamics of the (Sr1−xLax)3Ir2O7 system.

Highlights

We report on infrared spectroscopic studies of the electronic response of the (Sr1−xLax)3Ir2O7 system
We found that electron doping led to an insulator-metal transition that is reminiscent of the Mott transitions in strongly correlated 3d/4d transition metal oxides
Two broad peaks at about 0.4 and 0.8 eV represent the optical excitations between the Jeff bands, which will be discussed in detail later

Summary

Introduction

We report on infrared spectroscopic studies of the electronic response of the (Sr1−xLax)3Ir2O7 system. In the n = 1 and n = 2 members of the series, the electronic correlations in concert with the strong spin-orbit coupling were found to lead to the formation of an effective total angular momentum Jeff = 1/2 Mott state[2,3,4,5,6,7]. A scanning tunneling spectroscopy (STS) experiment of Sr3Ir2O7 in combination with density-functional-theory (DFT) calculations suggested a critical role of electronic correlations in the formation of a substantial charge gap of about 130 meV18. The. STS data further showed that the oxygen-vacancy-induced electronic structure changes were reminiscent of the filling-controlled Mott transitions in 3d/4d transition metal oxides. The sum rule and the extended Drude model analyses of our optical conductivity data revealed a substantial mass enhancement of the charge carriers in the metallic compound

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Conclusion