Condensation energy in strongly coupled superconductors
Condensation energy in strongly coupled superconductors
复制标题
强耦合超导体中的凝聚能
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
A. Chubukov
中科院分区：
文献类型：
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作者：
R. Haslinger;A. Chubukov
在自旋费米子模型的背景下，我们考虑了强耦合磁介质超导体的凝聚能Ec。我们认为，凝聚能量背后的实际物理比BCS理论丰富得多，并且考虑费米子和玻色子对凝聚能量的贡献是至关重要的。我们认为，在强耦合的λ>；>；1，凝聚能的增加是自旋激发反馈的结果，而费米子对Ec的贡献是正的，这是由于费米子的“脱衣服”反馈。此外，我们还认为，在强耦合时，同样的反馈效应可以解释动能的增加。我们还发现，BCS关系EcΔ2，其中A是配对能隙，仅对λ≤1成立。在较大的λ，Δ处，Ec不断增加并最终饱和，而Ec在λ∼2处通过极大值，然后在强耦合区域表现出减小。
We consider the condensation energy E c of strongly coupled magnetically mediated superconductors within the context of the spin-fermion model. We argue that the actual physics behind the condensation energy is much richer than in BCS theory, and that it is vital to take both the fermionic and bosonic contributions to the condensation energy into account. We argue that at strong coupling λ >> 1, the gain in the condensation energy is a result of the feedback on spin excitations, while the fermionic contribution to E c is positive due to an "undressing" feedback on the fermions. In addition we argue that the same feedback effect accounts for a gain in the kinetic energy at strong coupling. We also found that the BCS relation E c Δ 2 , where A is the pairing gap, only holds for λ ≤ 1. At larger λ, Δ keeps increasing and eventually saturates, while E c passes through a maximum at λ∼2 and then exhibits a decrease in the strong-coupling regime.