Phase Diagram of Nickelate Superconductors Calculated by Dynamical Vertex Approximation
Phase Diagram of Nickelate Superconductors Calculated by Dynamical Vertex Approximation
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DOI：
10.3389/fphy.2021.810394
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发表时间：
2022-01
期刊：
影响因子：
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通讯作者：
K. Held;L. Si;P. Worm;O. Janson;R. Arita;Z. Zhong;J. Tomczak;Motoharu Kitatani
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文献类型：
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作者：
K. Held;L. Si;P. Worm;O. Janson;R. Arita;Z. Zhong;J. Tomczak;Motoharu Kitatani
我们回顾了具有和不具有电子关联效应的镍酸盐超导体的电子结构。作为最小模型，我们确定了Ni3dx2−y2轨道加上A动量周围的口袋的单带Hubbard模型。然而，后者只是起到去耦合电子储存库的作用。这个库使得从名义上的锶掺杂到单带Hubbard模型的掺杂的谨慎转换是强制性的。我们的动力学平均场理论计算表明，Γ口袋、Nd4f轨道、氧2p和其他Ni3d轨道在超导掺杂体系中并不相关。如果存在拓扑同向氢或氧还原不完全，物理上就完全不同了。然后，出现了由Ni3dx2−y2和3d3z2−r2轨道主持的双能带物理.在最小模型的基础上，我们利用动力学顶点近似计算了实验前超导T_c-S_r掺杂x相图。对于像T_c这样一个出了名的难以确定的量，与实验的一致性令人惊讶地好。T_c随压力或压应变的增大而增大的预测也得到了实验证实。这支持了单带Hubbard模型加上一个电子储库是合适的最小模型。
We review the electronic structure of nickelate superconductors with and without effects of electronic correlations. As a minimal model, we identify the one-band Hubbard model for the Ni 3 d x 2 − y 2 orbital plus a pocket around the A-momentum. The latter, however, merely acts as a decoupled electron reservoir. This reservoir makes a careful translation from nominal Sr-doping to the doping of the one-band Hubbard model mandatory. Our dynamical mean-field theory calculations, in part already supported by the experiment, indicate that the Γ pocket, Nd 4f orbitals, oxygen 2p, and the other Ni 3d orbitals are not relevant in the superconducting doping regime. The physics is completely different if topotactic hydrogen is present or the oxygen reduction is incomplete. Then, a two-band physics hosted by the Ni 3 d x 2 − y 2 and 3 d 3 z 2 − r 2 orbitals emerges. Based on our minimal modeling, we calculated the superconducting T c vs. Sr-doping x phase diagram prior to the experiment using the dynamical vertex approximation. For such a notoriously difficult to determine quantity as T c , the agreement with the experiment is astonishingly good. The prediction that T c is enhanced with pressure or compressive strain has been confirmed experimentally as well. This supports that the one-band Hubbard model plus an electron reservoir is the appropriate minimal model.