Extended Data Figure 5 : Cuts of the Fermi surface of the equilibrium (black line) and transient crystal structures (red dashed line) at kz = 0.

From: Nonlinear lattice dynamics as a basis for enhanced superconductivity in YBa2Cu3O6.5

Extended Data Figure 5

In the equilibrium structure, the bands of the unfilled-chain Cu atoms give rise to pockets in the Fermi surface. The light-induced displacements shift the densities of states of these bands to lower energies, increasing the filling and reducing the pockets. Above a threshold of 0.8 Å√u, the O-deficient chain bands become fully filled, the pockets close and the Fermi surface consists solely of two-dimensional planar Cu sheets and one-dimensional filled-chain states. The Fermi surface is shown in the displaced state for amplitudes of 0.8 Å√u (left) and 1.2 Å√u (right).