Figure 10.

Cartoon picture for the Fermi surfaces and gap structures

(A and B) The Fermi surfaces and the gap amplitude at the cut k_z = 0. A d-wave gap is formed on the α Fermi pocket centered around Γ, and a full gap may appear on the β pocket. Actually, the Fermi surface on the α pocket at this cut looks very similar to that of underdoped cuprates.

(C and D) The Fermi surfaces and the gap amplitude at the cut k_z = π. A d-wave gap is formed on the α Fermi pocket centered around Z, now the Fermi surface becomes a closed square like mimicking that of overdoped cuprates, and a full gap may appear on the γ pocket around A. The height of the colored walls in (A) and (C) indicates the gap magnitude on each Fermi surface. The blue and red colors in (B) and (D) represent the gap signs. Adapted from Gu et al.¹⁷⁴