Optical and microwave study of Nd{sup 3+} ions in Nd{sub 2}O{sub 3}

Raman scattering and luminescence of the Nd{sup 3+}-ion crystal-field excitations in Nd{sub 2}O{sub 3} single crystal and polycrystalline powder are studied as a function of temperature and magnetic field. Splitting of Kramers doublets due to Nd{sup 3+}-Nd{sup 3+} interactions is not observed down to T=3.8K and no crystal-field{endash}phonon symmetry allowed coupling is detected. However, microwave dielectric measurements under magnetic field indicate that a magnetic phase transition due to Nd{sup 3+}-Nd{sup 3+} magnetic moment interactions occurs below 2 K. {copyright} {ital 1997} {ital The American Physical Society}