Effect of phase fluctuations on INS and NMR experiments in the   pseudo-gap regime of the underdoped cuprates
  We present a theory for inelastic neutron scattering (INS) and nuclear magnetic resonance (NMR) experiments in the pseudo-gap regime of the underdoped high-$T_c$ cuprates. We show that superconducting phase fluctuations greatly affect the temperature and frequency dependence of the spin-susceptibility, $\chi''$, probed by both experimental techniques. This result explains the appearance of a {\it resonance peak}, observed in INS experiments, below a temperature $T_0 > T_c$. In the same temperature regime, we find that the $^{63}$Cu spin-lattice relaxation rate, $1/T_1$, measured in NMR experiments, is suppressed. Our results are in qualitative agreement with the available experimental data. 
Harry Westfahl Jr. (1) and Dirk K. Morr (1 and 2) ((1) University of   Illinois at Urbana-Champaign, (2) Los Alamos National...