DYNAMIC SPIRAL STATE AT FINITE DOPING

We study doping effects in the antiferromagnetic state. It is shown that hole-driven spiral fluctuations will dominate over conventional spin waves in the long-wavelength, low-energy limit, leading to a disordered state at finite doping. In such a background, the single-hole propagator will lose its coherence beyond the characteristic scale of the spin correlation, whereas a pair of holes could still keep their coherent amplitude in the singlet channel. Superconducting condensation is discussed after the interlayer coupling is included.