Publication date: Jul 06, 2023
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] reciprocal-space 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 its integrated total is largest in the [001] direction and smallest in the [111] direction, in contrast to the experimentally measured trends in critical temperatures. This disagreement points to a non-BCS character of the superconductivity. Instead, the strong localization of λ in the soft optical modes around Γ suggests an importance of ferroelectric soft-mode fluctuations, which is supported by our findings that the mode-resolved λ values are strongly enhanced in polar structures. The inclusion of spin-orbit coupling has negligible influence on our calculated mode-resolved λ values.
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File name | Size | Description |
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README.txt
MD5md5:f4cb8a545b1067d7c14f012a81da4827
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1.8 KiB | README |
materialscloud_KTO_EPW.zip
MD5md5:1bd0b56398fa6ba3fdd8a48f970f5a23
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657.8 KiB | zip file containing all input files |
2023.132 (version v3) | Aug 28, 2023 | DOI10.24435/materialscloud:3t-k3 |
2023.105 (version v2) [This version] | Jul 06, 2023 | DOI10.24435/materialscloud:sn-xs |
2022.136 (version v1) | Nov 04, 2022 | DOI10.24435/materialscloud:7z-wx |