V Laboratory
Department of Physics
Nagoya University
Furocho, Chikusa, Nagoya

Electrical oscillation in SmS induced by a constant external voltage

In strong electric fields, the deviation from Ohm’s law, known as the nonlinear conduction, is often observed in semiconductors. Although the most cases are extrinsic due to a self-heating effect, several intrinsic nonlinear conduction behaviors have also been reported. In charge-density-wave and charge-ordered materials, for example, spontaneous electrical oscillation phenomena have been observed in constant external voltages, attributed to sliding excitation of density wave or melting of charge order in fields. In this study we find the electrical oscillation behavior in rare-earth narrow-gap semiconductor SmS at low temperatures. The present results can be explained well within a simple charging-discharging model in an electrical circuit consisting the resistance and the capacitance. The origin of discharging process can be an impact ionization due to the small band gap energy or an instability toward a metallic state inferred from the pressure-induced insulator-metal transition in SmS.

"Electrical oscillation in SmS induced by a constant external voltage"
by H. Takahashi, R. Okazaki, H. Taniguchi, I. Terasaki, M. Saito, K. Imura, K. Deguchi, N. K. Sato, and H. S. Suzuki
Phys. Rev. B 89, 195103 (2014).

(Figure) Electric current oscillation in SmS induced by constant external voltage.