Optical signatures of spin-orbit exciton in bandwidth-controlled S r2Ir O4 epitaxial films via high-concentration Ca and Ba doping

M. Souri, B. H. Kim, J. H. Gruenewald, J. G. Connell, J. Thompson, J. Nichols, J. Terzic, B. I. Min, G. Cao, J. W. Brill, A. Seo

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


We have investigated the electronic and optical properties of (Sr1-xCax)2IrO4 (x=0-0.375) and (Sr1-yBay)2IrO4 (y=0-0.375) epitaxial thin films, in which the bandwidth is systematically tuned via chemical substitutions of Sr ions by Ca and Ba. Transport measurements indicate that the thin-film series exhibits insulating behavior, similar to the Jeff=1/2 spin-orbit Mott insulator Sr2IrO4. As the average A-site ionic radius increases from (Sr1-xCax)2IrO4 to (Sr1-yBay)2IrO4, optical conductivity spectra in the near-infrared region shift to lower energies, which cannot be explained by the simple picture of well-separated Jeff=1/2 and Jeff=3/2 bands. We suggest that the two-peak-like optical conductivity spectra of the layered iridates originates from the overlap between the optically forbidden spin-orbit exciton and the intersite optical transitions within the Jeff=1/2 band. Our experimental results are consistent with this interpretation as implemented by a multiorbital Hubbard model calculation: namely, incorporating a strong Fano-like coupling between the spin-orbit exciton and intersite d-d transitions within the Jeff=1/2 band.

Original languageEnglish
Article number235125
JournalPhysical Review B
Issue number23
StatePublished - Jun 14 2017

Bibliographical note

Funding Information:
We thank C. H. Sohn for useful discussions and valuable comments. We acknowledge the support of National Science Foundation Grants No. DMR-1454200 for thin-film synthesis and characterizations, No. DMR-1265162 and No. DMR-1712101 for target synthesis, and No. DMR-1262261 for infrared spectroscopy. B.H.K. acknowledges support from the RIKEN iTHES Project for the numerical calculations.

Publisher Copyright:
© 2017 American Physical Society.

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


Dive into the research topics of 'Optical signatures of spin-orbit exciton in bandwidth-controlled S r2Ir O4 epitaxial films via high-concentration Ca and Ba doping'. Together they form a unique fingerprint.

Cite this