Friday, 7 November 2013, 10:00 AM, Physics 481

Charge Orders and Symmetry Breaking in Underdoped Cuprates

Yuxuan Wang, PhD Graduate Student, Department of Physics, University of Wisconsin (Madison)

Recent experiments in STM, neutron scattering, and x-ray have provided strong evidence that incommensurate static charge orders with momenta (Q,0) and (0,Q) exist in underdoped cuprates. In the same doping range and at higher temperatures, there is evidence for broken rotational symmetry and broken time-reversal symmetry. In this talk, I will present a theoretical study to explain the existence and doping dependence of the charge order. I will then discuss the interplay between different charge order parameters. Using a Ginzburg-Landau analysis, I show that rotational symmetry and time-reversal symmetry are both broken in the ground state.

Moreover, going beyond a mean-field analysis, I show that these discrete symmetries actually become broken at higher temperatures than the charge order onset temperature. I argue that such a state with broken discrete symmetries is a candidate for the enigmatic pseudogap in the cuprates and provides a “missing link” in understanding the cuprate physics.