We report measurements of the thermopower S and Nernst signal Syx in graphene in a magnetic field H. Both quantities show strong quantum oscillations vs the gate voltage Vg. Our measurements for Landau levels of index n ≠ 0 are in quantitative agreement with the edge-current model of Girvin and Jonson (GJ). The inferred off-diagonal thermoelectric conductivity αxy is consistent in magnitude with GJ's prediction. At the Dirac point (n=0), however, the width of the peak in αxy is very narrow. We discuss the physical meaning of the peak width and the puzzle raised by αxy for states at the Dirac point.
|Physical Review B - Condensed Matter and Materials Physics
|Published - Aug 27 2009
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics