Search for the {pi} Resonance in Two-Particle Tunneling Experiments of YBCO Superconductors

A recent theory of the resonant neutron scattering peaks in YBCO superconductors predicts the existence of a sharp spin-triplet two-particle collective mode (the {open_quotes}{pi} resonance{close_quotes}) in the normal state. In this paper, we propose an experiment in which the {pi} resonance could be probed directly in a two-particle tunneling measurement. {copyright} {ital 1997} {ital The American Physical Society}