High energy scales in the optical self-energy of the cuprate superconductors.
Using optical spectroscopy with a derivative technique, we find for the high Tc cuprate Bi2Sr2CaCu2O8+delta (Bi-2212) evidence for a new high energy scale at 900 meV beyond the two previously well-known ones at roughly 50 and 400 meV. The intermediate scale at 400 meV has recently been seen in angle-resolved photoemission spectroscopy experiments along the nodal direction as a large kink. In YBa2Cu3O6.50, the three energy scales are shifted to lower energy relative to Bi-2212 and we observe the emergence of a possible new high energy feature at 600 meV.
Hwang
J
J
Department of Physics and Astronomy, McMaster University, Hamilton, Ontario N1G 2W1, Canada.
Nicol
E J
EJ
Timusk
T
T
Knigavko
A
A
Carbotte
J P
JP