Dielectric and transient electrical response of SmB6 single crystals

We report results from an in-plane and out-of-plane impedance study on SmB6 single crystals, performed at low temperatures and over a wide frequency range. A universal equivalent circuit describes the dielectric behavior of this system across the transition, from surface to bulk dominated electrical conduction between 2 and 10 K. We identify the resistive, capacitive, and inductive contributions to the impedance. The equivalent inductance, obtained from fits to experimental data, drops drastically with increasing temperature, as the bulk starts to control electrical conduction. Self-sustained voltage oscillations, observed below 6 K across small crystals when biased with a dc current, point to a large SmB6 self-capacitance, likely brought by the surface states.

Automated summary

We conducted an impedance study on SmB6 single crystals in-plane and out-of-plane at low temperatures and a wide frequency range. The dielectric behavior of the system, ranging from surface to bulk dominated electrical conduction, was described by a universal equivalent circuit between 2 and 10 K. We identified the contributions of resistance, capacitance, and inductance to the impedance. The obtained equivalent inductance decreased significantly with increasing temperature, indicating the transition to bulk controlled electrical conduction. Self-sustained voltage oscillations below 6 K, observed when applying a dc current to small crystals, suggest a large self-capacitance of SmB6 likely due to surface states.