Angular Fluctuations of a Multicomponent Order Describe the Pseudogap of \(YBa_2Cu_3O_{6+x}\)

Abstract

The hole-doped cuprate high-temperature superconductors enter the pseudogap regime as their superconducting critical temperature, (T_c), falls with decreasing hole density. Recent x-ray scattering experiments in (YBa_2Cu_3O_{6+x}) observe incommensurate charge-density wave fluctuations whose strength rises gradually over a wide temperature range above (T_c), but then decreases as the temperature is lowered below (T_c). We propose a theory in which the superconducting and charge-density wave orders exhibit angular fluctuations in a six-dimensional space. The theory provides a natural quantitative fit to the x-ray data and can be a basis for understanding other characteristics of the pseudogap.