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First-principles calculation of electron-phonon coupling in doped KTaO₃

Tobias Esswein1*, Nicola A. Spaldin1*

1 Materials Theory, Department of Materials, ETH Zürich, Wolfgang-Pauli-Strasse 27, 8093 Zürich, Switzerland

* Corresponding authors emails: tobias.esswein@mat.ethz.ch, nicola.spaldin@mat.ethz.ch
DOI10.24435/materialscloud:7z-wx [version v1]

Publication date: Nov 04, 2022

How to cite this record

Tobias Esswein, Nicola A. Spaldin, First-principles calculation of electron-phonon coupling in doped KTaO₃, Materials Cloud Archive 2022.136 (2022), doi: 10.24435/materialscloud:7z-wx.


Motivated by the recent experimental discovery of strongly surface-plane-dependent superconductivity at surfaces of KTaO₃ single crystals, we calculate the electron-phonon coupling strength, λ, of doped KTaO₃ along the reciprocal-space high-symmetry directions. Using the Wannier-function approach implemented in the EPW package, we calculate λ across the experimentally covered doping range and compare its mode-resolved distribution along the [001], [110] and [111] directions. We find that the electron-phonon coupling is strongest in the optical modes around the Γ point, with some distribution to higher k values in the [001] direction. The electron-phonon coupling strength as a function of doping has a dome-like shape in all three directions, and is largest in the [001] direction and weakest in the [111] direction. This is in contrast to the experimentally measured critical temperatures, which are highest for the (111) plane, pointing to a non-BCS character of the superconductivity. The strong localization of λ in the soft optical modes around Γ suggests an importance of ferroelectric soft-mode fluctuations.

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electron-phonon coupling KTaO3 ab initio

Version history:

2022.136 (version v1) [This version] Nov 04, 2022 DOI10.24435/materialscloud:7z-wx