Experimental evidence for spin-energy coupling inCsNiF3

Abstract
The longitudinal spin response below the spin-wave energy has been observed in CsNiF3 in an applied magnetic field of 7 T and at temperature of 25 K by polarized-neutron inelastic scattering. The experimental results are compared with quantum-mechanical and classical theories predicting longitudinal response. The classical interpretation of a field-induced spin-energydensity coupling is found to be appropriate.