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

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{
  "updated": "2023-08-28T08:22:49.766582+00:00", 
  "created": "2023-08-26T13:55:19.335221+00:00", 
  "id": "1872", 
  "metadata": {
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    "mcid": "2023.132", 
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        "description": "Additional computational and convergence details", 
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    "contributors": [
      {
        "givennames": "Tobias", 
        "affiliations": [
          "Materials Theory, Department of Materials, ETH Z\u00fcrich, Wolfgang-Pauli-Strasse 27, 8093 Z\u00fcrich, Switzerland"
        ], 
        "familyname": "Esswein", 
        "email": "tobias.esswein@mat.ethz.ch"
      }, 
      {
        "givennames": "Nicola A.", 
        "affiliations": [
          "Materials Theory, Department of Materials, ETH Z\u00fcrich, Wolfgang-Pauli-Strasse 27, 8093 Z\u00fcrich, Switzerland"
        ], 
        "familyname": "Spaldin", 
        "email": "nicola.spaldin@mat.ethz.ch"
      }
    ], 
    "status": "published", 
    "keywords": [
      "electron-phonon coupling", 
      "KTaO3", 
      "ab initio"
    ], 
    "id": "1872", 
    "version": 3, 
    "license_addendum": null, 
    "conceptrecid": "1468", 
    "title": "First-principles calculation of electron-phonon coupling in doped KTaO\u2083", 
    "doi": "10.24435/materialscloud:3t-k3", 
    "is_last": true, 
    "publication_date": "Aug 28, 2023, 10:22:49", 
    "_oai": {
      "id": "oai:materialscloud.org:1872"
    }, 
    "license": "Creative Commons Attribution 4.0 International", 
    "edited_by": 576, 
    "description": "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, \u03bb, of doped KTaO3 along the reciprocal-space high-symmetry directions. Using the Wannier-function approach implemented in the EPW package, we calculate \u03bb 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 \u0393 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 \u03bb in the soft optical modes around \u0393 suggests an importance of ferroelectric soft-mode fluctuations, which is supported by our findings that the mode-resolved \u03bb values are strongly enhanced in polar structures. The inclusion of spin-orbit coupling has negligible influence on our calculated mode-resolved \u03bb values.", 
    "references": [
      {
        "url": "https://arxiv.org/abs/2210.14113", 
        "doi": "https://doi.org/10.48550/arXiv.2210.14113", 
        "type": "Preprint", 
        "citation": "T. Esswein, N. A. Spaldin, arXiv 2210.14113 (2022)."
      }
    ]
  }, 
  "revision": 2
}