Fig. 2.
Inelastic neutron measurements showing the suppression of the resonance mode under a c-axis-aligned magnetic field. (a) Zero field Q scans at ℏω = 10 meV at 5 K and 30 K on IN-8 with 60′-60′-S-60′-open collimations with neutron final energy fixed at Ef = 14.7 meV. The spectral weight increase below Tc demonstrates the presence of the resonance mode. (b) Ten-tesla Q scans at ℏω = 10 meV again on IN-8 showing no difference between the 5-K and 30-K intensities. Throughout our experiments, magnetic fields are always applied above 30 K and the samples were field-cooled to low temperature. (c) Q scans on BT-9 with 40′-48′-S-40′-80′ collimations showing the resonance intensity again at 10 meV in 0 T using Ef = 28 meV. (d) Identical Q scans at 5 K and 30 K showing the disappearance of the resonance mode under 6.8 T.