Correlated BCS wavefunction approach to unconventional superconductors

Pengfei Li; Kun Jiang; Jiangping Hu

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arXiv · 2309.02695

Correlated BCS wavefunction approach to unconventional superconductors

Pengfei Li·Kun Jiang·Jiangping Hu

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Abstract

We propose a modified BCS wavefunction as the ground state of a correlated superconductor with the correlation specified between $k$ and $-k$ electrons in the reciprocal space. Owing to this correlation, low-energy excitations are not conventional BCS Bogoliubov quasiparticles. They display at least four poles in the Green's function and their particle-hole weights in the tunneling and photon-emission spectrum become asymmetric. The superfluid density or superfluid stiffness also deviates from the BCS predictions with finite paramagnetic terms inside the total diamagnetic response. Moreover, a $d$-wave correlated pairing state becomes robust against weak disorders. Hence, this state can explain many mysterious features observed in unconventional superconductors like cuprates.

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Pengfei Li, Kun Jiang, Jiangping Hu. 2023-09-06. Correlated BCS wavefunction approach to unconventional superconductors. https://arxiv.org/abs/2309.02695

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