Wide applicability of high-Tc pairing originating from coexisting wide and incipient narrow bands in quasi-one-dimensional systems
Wide applicability of high-Tc pairing originating from coexisting wide and incipient narrow bands in quasi-one-dimensional systems
复制标题
源自准一维系统中共存的宽带和初期窄带的高温配对的广泛适用性
DOI：
10.1103/physrevb.97.014516
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发表时间：
2018
影响因子：
3.7
通讯作者：
and Kazuhiko Kuroki
中科院分区：
文献类型：
--
作者：
Karin Matsumoto;Daisuke Ogura;and Kazuhiko Kuroki
我们研究超导性的哈伯德模型中的各种准一维晶格与共存的宽和窄的带起源于多个网站内的一个单元格，其中每个网站对应于一个单一的轨道。研究的系统是两条腿和三条腿的梯子，钻石链，和十字形梯子。这些一维晶格弱耦合形成二维（准一维）晶格，并采用涨落交换近似研究自旋涨落介导的超导性。当其中一个带是完全平坦的并且与宽带相交的费米能级位于平坦带附近但不在平坦带内时，发现由于宽带的轻电子质量和由于平带的大态密度而产生的强配对相互作用的结合，由带间散射过程产生的超导电性被强烈增强。即使当窄带具有有限的带宽时，配对机制仍然起作用，因为窄带的边缘由于其大的态密度而起到平坦带的作用。结果表明，由于在准一维系统中共存的宽和“初期”窄带的高配对机制的广泛适用性。
We study superconductivity in the Hubbard model on various quasi-one-dimensional lattices with coexisting wide and narrow bands originating from multiple sites within a unit cell, where each site corresponds to a single orbital. The systems studied are the two-leg and three-leg ladders, the diamond chain, and the crisscross ladder. These one-dimensional lattices are weakly coupled to form two-dimensional (quasi-one-dimensional) ones, and the fluctuation exchange approximation is adopted to study spin-fluctuation-mediated superconductivity. When one of the bands is perfectly flat and the Fermi level intersecting the wide band is placed in the vicinity of, but not within, the flat band, superconductivity arising from the interband scattering processes is found to be strongly enhanced owing to the combination of the light electron mass of the wide band and the strong pairing interaction due to the large density of states of the flat band. Even when the narrow band has finite bandwidth, the pairing mechanism still works since the edge of the narrow band, due to its large density of states, plays the role of the flat band. The results indicate the wide applicability of the high-pairing mechanism due to coexisting wide and “incipient” narrow bands in quasi-one-dimensional systems.