Kowalski Nicolas, Dash Sidhartha Shankar, Sémon Patrick, Sénéchal David, Tremblay André-Marie
Département de physique, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada.
Institut quantique, Université de Sherbrooke, Sherbrooke, QC J1K 2R1, Canada.
Proc Natl Acad Sci U S A. 2021 Oct 5;118(40). doi: 10.1073/pnas.2106476118. Epub 2021 Sep 30.
Experiments have shown that the families of cuprate superconductors that have the largest transition temperature at optimal doping also have the largest oxygen hole content at that doping [D. Rybicki et al., 7, 1-6 (2016)]. They have also shown that a large charge-transfer gap [W. Ruan et al., 61, 1826-1832 (2016)], a quantity accessible in the normal state, is detrimental to superconductivity. We solve the three-band Hubbard model with cellular dynamical mean-field theory and show that both of these observations follow from the model. Cuprates play a special role among doped charge-transfer insulators of transition metal oxides because copper has the largest covalent bonding with oxygen. Experiments [L. Wang et al., arXiv [Preprint] (2020). https://arxiv.org/abs/2011.05029 (Accessed 10 November 2020)] also suggest that superexchange is at the origin of superconductivity in cuprates. Our results reveal the consistency of these experiments with the above two experimental findings. Indeed, we show that covalency and a charge-transfer gap lead to an effective short-range superexchange interaction between copper spins that ultimately explains pairing and superconductivity in the three-band Hubbard model of cuprates.
实验表明，在最佳掺杂时具有最高转变温度的铜酸盐超导体家族，在该掺杂下也具有最大的氧空穴含量[D. 雷比茨基等人，《7》，1 - 6 (2016)]。实验还表明，一个大的电荷转移能隙[W. 阮等人，《61》，1826 - 1832 (2016)]，这是一个在正常态下可获取的量，对超导性不利。我们用格点动力学平均场理论求解三带哈伯德模型，并表明这两个观察结果都源于该模型。在过渡金属氧化物的掺杂电荷转移绝缘体中，铜酸盐起着特殊作用，因为铜与氧具有最大的共价键。实验[L. 王等人，arXiv预印本。https://arxiv.org/abs/2011.05029(于2020年11月10日访问)]也表明，超交换是铜酸盐中超导性的起源。我们的结果揭示了这些实验与上述两个实验发现的一致性。确实，我们表明共价性和电荷转移能隙导致了铜自旋之间有效的短程超交换相互作用，这最终解释了铜酸盐三带哈伯德模型中的配对和超导性。
