Competing Unconventional Charge-Density-Wave States in Cuprate Superconductors: Spin-Fluctuation-Driven Mechanism

To understand the origin of unconventional charge-density-wave (CDW) states in cuprate superconductors, we establish the self-consistent CDW equation, and analyze the CDW instabilities based on the realistic Hubbard model, without assuming any q-dependence and the form factor. Many higher-order many-body processes, which are called the vertex corrections, are systematically generated by solving the CDW equation. When the spin fluctuations are strong, the uniform q = 0 nematic CDW with d-form factor shows the leading instability. The axial nematic CDW instability at q = Q(a) = (delta, 0) (delta approximate to pi/2) is the second strongest, and its strength increases under the static uniform CDW order. The present theory predicts that uniform CDW transition emerges at a high temperature, and it stabilize the axial q = Qa CDW at T = T-CDW. It is confirmed that the higher-order Aslamazov-Larkin processes cause the CDW orders at both q = 0 and Q(a).