Scanning tunneling spectroscopy studies of charge ordering and rotational symmetry breaking in the high-temperature superconductor Bi2Sr2CaCu2O8+x

Condensed Matter Seminars

Speaker: Eduardo H. da Silva Neto, University of British Columbia
Date & Time: November 7, 2013 14:00 - 15:00
Location: UBC, Hennings 318
Local Contact: Andrea Damascelli
Intended Audience: Graduate

Understanding the mechanism of superconductivity and its interplay with other possible ordered states in high transition temperature (T_c) cuprate superconductors remains one of the most significant challenges in all of condensed matter physics. In this talk I will discuss scanning tunneling microscopy (STM) measurements which establish the formation of charge ordering in the high-temperature superconductor Bi₂Sr₂CaCu₂O_8+x (Bi-2212). The STM results show that this charge ordering leaves a distinct signature in spectroscopic measurements, thereby indicating that it is likely related to the organization of holes in a doped Mott insulator. Doping- and temperature-dependent spectroscopic measurements, supported by resonant elastic x-ray scattering, establish the competing nature between charge ordering and superconductivity in Bi-2212. Finally, recent STM measurements have been used as evidence for electronic nematicity (C₄ to C₂ symmetry breaking) in the cuprates. If time permits, I will also discuss investigations of the influence of anisotropic tip structures on STM measurements, and establish, with a simple model calculation, the presence of a tunneling interference effect that induces an artificial nematic signal in conductance maps. Experimentally this effect is demonstrated to occur in different families of correlated electron systems.