Thermodynamic Constraints on the Magnetic Field Dependence of the Neutron Resonance in Cuprate Superconductors

Abstract

In order to test the recently proposed connection between the neutron resonance and the specific heat anomaly in cuprates, the experimental specific heat data on $YBa_2Cu_3O_{6.93}$ and a theoretical estimate of the single particle fermionic contribution to the specific heat is used to provide an upper bound for the intensity of the neutron peak. The deduced peak intensity is similar in magnitude and temperature dependence to that observed in neutron scattering experiments, and it is constrained to decrease strongly under the influence of moderate magnetic fields oriented along the c-axis of the crystal. An explanation is proposed for the predicted suppression, based on the observation that the resonance intensity is very sensitive to superconducting phase correlations.