Resonant neutron peak and the symmetry of the superconducting order parameter inYBa2Cu3O7

Abstract

It is shown that the $s^{\pm }$-wave pairing state proposed to interpret the resonant neutron peak observed in ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_7$ corresponds to an interlayer pairing state and it has a drastically different magnetic behavior (in the odd channel) in the long wavelength limit as compared to the $d_{x^2-y^2}$-wave state. It is found that the $d_{x^2-y^2}$-wave state provides a more natural interpretation for the resonant peak, especially its sharpness in the momentum space which is a direct consequence of the d-wave symmetry of the order parameter. An experiment is proposed to decide which kind of pairing state is actually realized in ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_7.$