Charge fluctuation in Sm3Te4

Ultrasonic measurements for a valence-fluctuation compound Sm3Te4 have been performed. Considerable dispersion around 120 K due to a thermal hopping m otion of 4f-electron among Sm2+ and Sm3+ has been observed in the ultrasoni c attenuation The relaxation time of the charge fluctuation 2 pi tau become s infinite at low temperatures following as tau = tau(0)exp(E/k(B) T), here 2 pi tau(0) = 2.5 x 10(-13) s and E = 0.135 eV. The In T dependence of the elastic constants similar to a two-level system of amorphous glass compoun ds is observed at low temperatures below 15 K. These results indicate a two -level system of the 4f-electron tunneling in the random potential of Sm2and Sm3+ ions due to the charge glass state. (C) 2000 Elsevier Science B.V. All rights reserved.