Planckian scaling behavior of Bi2Sr2CaCu2O8+d at a critical doping in the overdoped region
Jungseek Hwang
Sungkyunkwan University
Wednesday, January 15, 2025
2:00 p.m.
In-person: QNC 1201
Abstract: The Planckian scaling behavior may take place in correlated electron systems at a quantum critical point. Here, we investigated Bi2Sr2CaCu2O8+d (Bi-2212) single-crystal samples in the overdoped region using infrared/optical spectroscopy. We obtained the optical self-energy in the extended Drude formalism. From the real parts of the optical self-energy, we observed that the optical resonance mode (ORM) disappeared at a critical doping (pc ~ 0.232) inside the superconducting dome in the phase diagram. As doping approached the critical doping, the ORM rapidly broadened, indicating an increase in associated critical fluctuations. Both the optical scattering rate and effective mass of the Bi-2212 sample (p = 0.231) near the critical doping exhibited Planckian () scaling behavior. The Planckian scaling behavior gradually progressed as the material system approached the critical doping. Observation of scaling behavior at the critical doping suggests that the critical doping is a quantum critical point (QCP). Furthermore, the electron-boson spectral density (EBSD) function obtained from the optical scattering rate became less temperature- and frequency-dependent as the doping approached the critical doping. We will discuss the possibility of quantum criticality at the critical doping.