Thermal Probe of Fractional Quantum Hall States in Bilayer Graphene

Measuring thermodynamic properties such as thermoelectric power (TEP) of a system can offer a way which is distinct from other techniques, particularly when it comes to studying fractional quantum hall states at half-filled Landau Levels (LLs). It has been shown that in a clean, non-interacting 2D electron system, TEP is proportional to the transport entropy of the 2D electron system. In the presence of a high magnetic field for strongly interacting electrons, the relation between TEP and entropy remains the same, which was also proved in previous works. This characteristic makes TEP a powerful measurement technique for studying statistical properties of FQH states, as the entropy carried by non-Abelian quasiparticles is predicted to be anomalously large. In our work, we perform magneto-TEP measurements of high-quality Bernal stacked bilayer graphene (BLG) because BLG has recently emerged as a new platform to study even denominator states. In our experiment, we observed well-developed FQH states even at a relatively low magnetic field. Our result indicates that thermopower as a measure of entropy is more sensitive to probe FQH states than resistivity measurements. We also perform temperature and magnetic field dependence to further study the observed FQH states.