| dc.description |
The magnetic properties of the unconventional mixed-valence compound Sm<sub>3</sub> Te<sub>4</sub> have been studied by inelastic neutron scattering. Time-of-flight experiments with different incident energies (E<sub>i</sub> = 300 meV, 67 meV and 3.2 meV) and energy resolutions have been performed on isotopic (low-absorption) <sup>154</sup> Sm<sub>3</sub> Te<sub>4</sub> and on the reference compound La<sub>3</sub> Te<sub>4</sub> . Spectral contributions from two coexisting valence states Sm<sup>2+</sup> and Sm<sup>3+</sup> were clearly identified. In contrast to previous results for SmB<sub>6</sub> , the spectra can be analysed in terms of well defined 4f <sup>5</sup> and 4f <sup>6</sup> local moments subjected to the crystal field. However, the data reveal that di- and trivalent ions, which occupy identical crystallographic sites, feel quite different crystal-field potentials. Quasielastic scattering was found to exist down to the minimum temperature (1.5 K) of the measurements, with a half-width of about 0.45 meV. This implies that spin fluctuations, with a much higher fluctuation rate than the valence fluctuations reported in a recent NMR study, exist just above the spin-glass transition. |
