BCS theory on a flat band lattice
BCS theory on a flat band lattice
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DOI：
10.1016/j.physc.2007.03.393
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发表时间：
2007-09-01
影响因子：
1.7
通讯作者：
Furukawa, N.
中科院分区：
文献类型：
--
作者：
Miyahara, S.;Kusuta, S.;Furukawa, N.
研究电子在平带晶格上的多体效应是很重要的，因为色散的平坦性可能导致存在相互作用时的不稳定性。为了阐明平坦色散对超导性的影响，我们在平均场近似下研究了一个简单的两带BCS哈密顿量，其中一个带具有平坦色散。超导带隙Δ和临界温度Tc强烈地依赖于对耦合常数V，特别是当耦合常数较小时，Δ和Tc与V成正比，这与单带BCS的情况有很大的不同。与普通BCS系统相比，由于平坦带的存在，实现了更高的T-c。(c)2007 Elsevier B. V.保留所有权利。
It is important to study the many-body effects of the electrons on the flat band lattice, since the flatness of the dispersion may lead to instabilities in the presence of interactions. To clarify the effects of flat dispersion for superconductivity, we investigate a simple two-band BCS Hamiltonian, where one of the bands has a flat dispersion, in the mean field approximation. A superconducting gap Delta and a critical temperature T-c strongly depend on the pairing coupling constant V. Especially, for small coupling constant, Delta and T-c are proportional to V, which are quite different from the single band BCS cases. Higher T-c, compared to the normal BCS system, are realized due to the existence of the flat band. (c) 2007 Elsevier B.V. All rights reserved.