Multistage electronic nematic transitions in cuprate superconductors: A functional-renormalization-group analysis

Recently, complex rotational symmetry-breaking phenomena have been discovered experimentally in cuprate superconductors. To find the realized order parameters, we study various unconventional charge susceptibilities in an unbiased way by applying the functional-renormalization-group method to the d-p Hubbard model. Without assuming the wave vector of the order parameter, we reveal that the most dominant instability is the uniform (q = 0) charge modulation on the p(x) and p(y) orbitals, which possesses d symmetry. This uniform nematic order triggers another nematic p-orbital density wave along the axial (Cu-Cu) direction at Q(a) approximate to (pi/2,0). It is predicted that uniform nematic order is driven by the spin fluctuations in the pseudogap region, and another nematic density-wave order at q = Q(a) is triggered by the uniform order. The predicted multistage nematic transitions are caused by Aslamazov-Larkin-type fluctuation-exchange processes.