Low energy nuclear spin excitations in NdGaO3

We have investigated the low energy excitations in NdGaO3 in the μeV range by a back scattering neutron spectrometer. The energy scans on a NdGaO3 single revealed inelastic peaks at E=1.650±0.004 μeV at T=50 mK on both energy gain and energy loss sides. The inelastic peaks move gradually towards lower energy with increasing temperature and finally merge with the elastic peak at the electronic magnetic ordering temperature TN≈975 mK. We interpret the inelastic peaks to be due to the transition between hyperfine-split nuclear level of the 143Nd and 145Nd isotopes with spin I=7/2.