Nuclear ordering and excitations in NdFeO3

The energy splitting of Nd nuclear levels and Nd nuclear polarization in NdFeO3 have been studied by using high resolution inelastic neutron backscattering with simultaneous neutron diffraction at temperatures between 100 mK and 15 K. Inelastic peaks are observed below 4.5 K with a corresponding energy splitting ΔE=1.24μeV below 0.9 K. The Nd nuclear magnetic moments are polarized below 1 K with a maximal polarization of 17% observed at 100 mK. Both these phenomena directly observed in NdFeO3 are described by assuming a magnetic hyperfine coupling model. It is found that the present experimental data on NdFeO3 and the literature data concerning Nd2CuO4 can be consistently described by using the same value of the magnetic hyperfine coupling constant A=1.10(5)μeV/μB.