Enhancement of incoherent elastic scattering with magnetic ordering in the energy spectra of nuclear resonant scattering

We have observed the extreme enhancement of elastic peak intensity in the energy spectrum of nuclear resonant scattering by 57Fe in CaFeO3 following magnetic phase transition, while the inelastic scattering part of the spectrum hardly changed. This enhancement effect clearly indicates that the sum of the elastic and inelastic parts changes as the temperature changes, that is, it is not conserved. This effect is thought to be due to the change of the coherent scattering channel caused by the splitting of the nuclear energy level induced by magnetic phase transition without structural phase transition. This effect shows that the splitting in the energy ranges on the neV order emerges in the energy spectrum of the nuclear resonant scattering spectrum measured with the resolution function on the meV order. Therefore, the energy spectra of incoherent nuclear resonant scattering can be applied to the study of the phase transition of electronic states in addition to phonon states, and the origin of the phase transition will be distinguished clearly. (author)