Three observations on the ARPES data of the cuprate superconductors - what the AF spin fluctuation can do and what it cannot Tao Li Renmin University of China, Beijing, China

We discuss the origin of the pseudogap phenomena in the cuprate superconductors from the perspective of the spin-Fermion model. We find that the vanishing of the pseudogap around (\pi,0) as observed recently in Pr_1.3−xLa_0.7Ce_xCuO₄ is consistent with the AF band folding picture of the pseudogap in the electron-doped cuprates, if we assume a strongly momentum dependent quasi-particle scattering rate on the Fermi surface[1,4]. However, we find that the pseudogap in the hole-doped cuprates is unlikely an AF band folding gap. In particular, we show that electron pairing is indispensable to eliminate the Fermi level crossing along (\pi,0)-(\pi,\pi) in a way consistent with the ARPES observation on the underdoped Bi-2201 system around T*[2,4]. Nevertheless, we find that the AF spin fluctuation in the hole-doped cuprates is responsible for the high energy hump structure, the mismatch between the hump back-bending momentum and the bare Fermi momentum, and in particular, the extremely flatness of the anti-nodal quasi-particle dispersion in the superconducting state [3,4].

[1] Hario et al, arXiv: 1801.04147.
[2] Hashimoto et al, Nat. Phys. 6, 414 (2010).
[3] R.H. He et al, Science 331, 1579 (2011).
[4] Tao Li and Da-Wei Yao, arXiv: 1803.08226; arXiv:1805.05530; arXiv:1805.04883.