Thermopower Measurement in the Fractional Quantum Hall Regime in Bilayer Graphene

Measurements of thermoelectric voltages can provide a sensitive probe of the entropy carried by charge carriers in a system, probing the properties of interesting electrical ground states. In particular, attempts have been made to use magnetothermopower measurements to identify the ground state of even denominator fractional quantum hall (FQH) states, such as the 5/2 FQH state in GaAs 2D electron gases [1,2]. Theory predicts that the filling fraction dependent magnetothermopower can probe the charge of quasi-particles in this strongly correlated quantum system and provide evidence for the possible presence of a non-abelian ground state [3]. In this presentation, we will present magnetothermopower measurements in Bernal stacked bilayer graphene in the quantum limit, where measure the magneto-conductance and thermopower in the integer quantum Hall ferromagnetism and FQH regimes. We will discuss our progress on performing thermoelectric measurements on high quality bilayer graphene samples at high field and low temperature where fractional quantum Hall states are present, with particular focus on determining the entropy of the quasiparticles of even denominator fractions to determine the ground state.



[1] Chickering et al., PRB, 81, 245319 (2010).

[2] Chickering et al., PRB, 87, 075302 (2010).

[3] Kun Yang and B. I. Halperin, PRB, 79, 115317 (2009).