Events at Physics |
band hybridization lead to a diverging resistance at low temperature.<br>
The resistance divergence ends at about 3 Kelvin, a behavior recently<br>
demonstrated to arise from the surface conductance. However, questions<br>
remain whether and where a topological surface state exists. Quantum<br>
oscillations have not been observed to map the Fermi surface. We solve<br>
the problem by resolving the Landau Level quantization and Fermi<br>
surface topology using torque magnetometry. The observed angular<br>
dependence of the Fermi surface cross section suggests two-dimensional<br>
surface states on the (101) and (100) plane. Furthermore, similar to<br>
the quantum Hall states for graphene, the tracking of the Landau<br>
Levels in the infinite magnetic field limit points to -1/2, the Berry<br>
phase contribution from the 2D Dirac electronic state.