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High-pressure versus isoelectronic doping effect on the honeycomb iridate Na$_2$IrO$_3$
- Source :
- Phys. Rev. B 96, 195137 (2017)
- Publication Year :
- 2017
-
Abstract
- We study the effect of isoelectronic doping and external pressure in tuning the ground state of the honeycomb iridate Na$_2$IrO$_3$ by combining optical spectroscopy with synchrotron x-ray diffraction measurements on single crystals. The obtained optical conductivity of Na$_2$IrO$_3$ is discussed in terms of a Mott insulating picture versus the formation of quasimolecular orbitals and in terms of Kitaev-interactions. With increasing Li content $x$, (Na$_{1-x}$Li$_x$)$_2$IrO$_3$ moves deeper into the Mott insulating regime and there are indications that up to a doping level of 24\% the compound comes closer to the Kitaev-limit. The optical conductivity spectrum of single crystalline $\alpha$-Li$_2$IrO$_3$ does not follow the trends observed for the series up to $x=0.24$. There are strong indications that $\alpha$-Li$_2$IrO$_3$ is less close to the Kitaev-limit compared to Na$_2$IrO$_3$ and closer to the quasimolecular orbital picture. Except for the pressure-induced hardening of the phonon modes, the optical properties of Na$_2$IrO$_3$ seem to be robust against external pressure. Possible explanations of the unexpected evolution of the optical conductivity with isolectronic doping and the drastic change between $x=0.24$ and $x=1$ are given by comparing the pressure-induced changes of lattice parameters and the optical conductivity with the corresponding changes induced by doping.<br />Comment: 12 pages, 6 figures, accepted for publication in Phys. Rev. B
- Subjects :
- Condensed Matter - Strongly Correlated Electrons
Subjects
Details
- Database :
- arXiv
- Journal :
- Phys. Rev. B 96, 195137 (2017)
- Publication Type :
- Report
- Accession number :
- edsarx.1711.00713
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1103/PhysRevB.96.195137