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Unlikelihood of a phonon mechanism for the high-temperature superconductivity in La 3 Ni 2 O 7

You, Jing-Yang [National University of Singapore (Singapore); University of Southern California, Los Angeles, CA (United States)]·Zhu, Zien [University of Southern California, Los Angeles, CA (United States)] (ORCID:0009000818761373)·Del Ben, Mauro [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)]·Chen, Wei [National University of Singapore (Singapore)]·Li, Zhenglu [University of Southern California, Los Angeles, CA (United States)] (ORCID:0000000238519241)
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Abstract

The discovery of ~80 K superconductivity in nickelate La 3 Ni 2 O 7 under pressure has ignited intense interest. Here, we present a comprehensive first-principles study of the electron-phonon (e-ph) coupling in La 3 Ni 2 O 7 and its implications on the observed superconductivity. Our results conclude that the e-ph coupling is too weak (with a coupling constant λ ≲ 0.5) to account for the high T c , albeit interesting many-electron correlation effects exist. While Coulomb interactions (via GW self-energy and Hubbard U) enhance the e-ph coupling strength, electron doping (oxygen vacancies) introduces no major changes. Additionally, different structural phases display varying characteristics near the Fermi level, but do not alter the conclusion. The e-ph coupling landscape of La 3 Ni 2 O 7 is intrinsically different from that of infinite-layer nickelates. These findings suggest that a phonon-mediated mechanism is unlikely to be responsible for the observed superconductivity in La 3 Ni 2 O 7 , pointing instead to an unconventional nature.

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75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITYElectronic structureSuperconducting properties and materials

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You, Jing-Yang [National University of Singapore (Singapore); University of Southern California, Los Angeles, CA (United States)], Zhu, Zien [University of Southern California, Los Angeles, CA (United States)] (ORCID:0009000818761373), Del Ben, Mauro [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)], Chen, Wei [National University of Singapore (Singapore)], Li, Zhenglu [University of Southern California, Los Angeles, CA (United States)] (ORCID:0000000238519241). 2025-01-06. Unlikelihood of a phonon mechanism for the high-temperature superconductivity in La 3 Ni 2 O 7. https://doi.org/10.1038/s41524-024-01483-4

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