Thermoelectric signals of state transition in polycrystalline SmB6

TL;DR

This study investigates thermoelectric properties of polycrystalline SmB6, revealing a transition from bulk to surface conduction around 12 K, which highlights the potential of thermotransport measurements to characterize topological insulator states.

Contribution

It provides the first detailed thermoelectric analysis of SmB6 across a broad temperature range, identifying a key transition in conduction mechanisms.

Findings

Seebeck coefficient transitions from T-1 to T around 12 K

Evidence of transition from 3D bulk to 2D surface conduction

Thermotransport measurements can characterize topological state transitions

Abstract

Topological Kondo insulator SmB6 has attracted quite a lot of attentions from condensed matter physics community. A number of unique electronic properties, including low- temperature resistivity anomaly, 1D electronic transport and 2D Fermi surfaces have been observed in SmB6. Here, we report on thermoelectric transport properties of polycrystalline SmB6 over a broad temperature from 300 K to 2 K. An anomalous transition in the temperature-dependent Seebeck coefficient S from S(T) ~ T-1 to S(T) ~ T was observed around 12 K. Such a transition demonstrates a transition of conductivity from 3D metallic bulk states to 2D metallic surface states with insulating bulk states. Our results suggest that the thermotransport measurements could be used for the characterization of state transition in topological insulators.