This model reasonably explains the observed oscillation phenomenon, implying the existence of a possible instability toward a conductive state driven by the electric field.

Physical Review B

We have observed a persistent voltage oscillation induced by constant external electric fields in the nonmagnetic narrow-gap semiconductor SmS. This oscillation appears with a large nonlinear conduction in a relatively low electric field of a few kV/cm. We find that the oscillation frequency clearly changes on addition of an external capacitor parallel to the sample, indicating that the oscillation does not arise from the Joule heating effect. This oscillation is analyzed in terms of a carrier charging-discharging model, which is associated with an electric-field-induced insulator-to-metal transition as proposed in the oxide insulator VO${}_{2}$. This model reasonably explains the observed oscillation phenomenon, implying the existence of a possible instability toward a conductive state driven by the electric field.

This model reasonably explains the observed oscillation phenomenon, implying the existence of a possible instability toward a conductive state driven by the electric field.

Electrical oscillation in SmS induced by a constant external voltage