Illuminating a Second 'Kink' in High-Tc Superconductors

“Big kink” (left) vs. “small kink” (right). a) OP91 BSCCO (T=10K). b) Brillouin zone (BZ) and Fermi surface (FS) for BSCCO (solid line) and LBCO (dashed line). Straight lines represent the momentum lines probed in the spectra with correspondingly colored dispersion. c) and d) LBCO spectra at x=0.125 for two different momentum lines as indicated in b). e) ARPES intensity from the nodal line in superconducting state in optimally doped BSCCO. The velocity or rate of dispersion changes in the vicinity of the Fermi level, resulting in a “kink” in dispersion at ~60 meV bellow the Fermi level. “Small kink” image from “Evidence for Quantum Critical Behavior in the Optimally Doped Cuprate Bi2Sr2CaCu2O8+d,” T. Valla, A. V. Fedorov, P. D. Johnson, B. O. Wells, Q. Li, G. D. Gu, and N. Koshizuka, Science 285, 2110 (1999).