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Abstract It has been suggested that Ba3In2O6might be a high-Tcsuperconductor. Experimental investigation of the properties of Ba3In2O6was long inhibited by its instability in air. Recently epitaxial Ba3In2O6with a protective capping layer was demonstrated, which finally allows its electronic characterization. The optical bandgap of Ba3In2O6is determined to be 2.99 eV in-the (001) plane and 2.83 eV along thec-axis direction by spectroscopic ellipsometry. First-principles calculations were carried out, yielding a result in good agreement with the experimental value. Various dopants were explored to induce (super-)conductivity in this otherwise insulating material. NeitherA- norB-site doping proved successful. The underlying reason is predominately the formation of oxygen interstitials as revealed by scanning transmission electron microscopy and first-principles calculations. Additional efforts to induce superconductivity were investigated, including surface alkali doping, optical pumping, and hydrogen reduction. To probe liquid-ion gating, Ba3In2O6was successfully grown epitaxially on an epitaxial SrRuO3bottom electrode. So far none of these efforts induced superconductivity in Ba3In2O6,leaving the answer to the initial question of whether Ba3In2O6is a high-Tcsuperconductor to be ‘no’ thus far.
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Investigation of pressure-driven superconductivity in TlInTe 2 : an ab initio study
Abstract The Zintl compound TlInTe2is an intriguing material because of its outstanding thermoelectric properties at ambient pressure. Interestingly, it has recently been found that TlInTe2exhibits a V-shape dependence of the superconducting critical temperature (Tc) under increasing pressure, which has been linked to the reversed behavior of the Raman active Agphonon mode and anharmonic effects. In this study, we have performed first-principles calculations of the electron-phonon interactions and the superconducting properties of TlInTe2in order to understand this unusual pressure-induced response. In contrast to experiment, we find a dome-shaped pressure-induced dependence ofTcwith a maximum value of 0.23 K at 18 GPa, significantly lower than the experimental results. Electron doping has the potential to adjust theTcto fall within the experimental range, but it necessitates considerably high levels of doping. Furthermore, our analysis of the phonon spectra and phonon lifetimes, including anharmonic effects, show that anharmonicity is unlikely to influence the superconducting properties of TlInTe2. It remains an open question whether there is indeed an unusual V-shapeTcdependence with pressure or whether the phonon-mediated theory of superconductivity used here breaks down in this system.
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- Award ID(s):
- 2035518
- PAR ID:
- 10524623
- Publisher / Repository:
- IOP Publishing
- Date Published:
- Journal Name:
- Physica Scripta
- Volume:
- 99
- Issue:
- 8
- ISSN:
- 0031-8949
- Format(s):
- Medium: X Size: Article No. 085962
- Size(s):
- Article No. 085962
- Sponsoring Org:
- National Science Foundation
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