We have performed 77Se NMR studies on a semiconducting and valence-fluctuating compound Sm3SO4 and a reference system Sm2Se3 with particular emphasis on temperature- and frequency-dependences of the nuclear transverse (1/T2) as well as longitudinal (1/T1) relaxation rates. 1/72 in Sm3Se4 shows a dramatic increase with decreasing temperature below 160 K, which occurs neither in 1/ Tj of Sms 864 nor in 1 / T2 = 1 /T1 of Sm2 Se3. Moreover, markedf2-variation with the resonance frequency /has been observed in I/T2 of Sm3Se4 in this temperature range. Discussions are made on how 77Se NMR can probe the valence-fluctuation (VF) phenomena, and the observed various features of 77Se NMR are shown to be explained quite consistently in terms of the temperature-activated VF. As far as the present authors know, this is the first NMR observation of the VF in rare-earth compounds.
ASJC Scopus subject areas