Lattice Instability in High Temperature Superconducting Cuprates and FeAs Systems: Polarons Probed by EXAFS

Figure 1

In-plane structure of the conducting layer in LaFeAsO_1−𝑥F_𝑥 (a) and La_1−𝑥Sr_𝑥CuO₄ (b). Use of polarization dependence (E//ab) XAS measurement can probe the planar local lattice projected onto the 𝑎𝑏-plane.

(a)

(b)