Laboratory for Solid State Physics, ETH ZurichIn this talk I will present two solutions to this problem. In bilayer graphene a bandgap arises for vertical electric fields. We demonstrate that a split-gate arrangement can be used to define a narrow 1D ballistic channel. An additional well positioned top gate allows to pinch off the channel. Furthermore a series of plateau-like features occurs when the channel is opened. An interesting level scheme arises in particular for high magnetic fields. Another approach is based on MoS2 encapsulated between layers of BN to obtain best electronic quality. At low magnetic fields we observe a degeneracy of 6, which is explained by the 3-fold valley degeneracy in the conduction band of MoS2 plus a factor of 2 for spin-degeneracy. In a quantum point contact again conductance pinch-off and quantization is observed. 2D materials have improved to an extent, that novel electronic quantum devices can be realized with great promise.
1. H. Overweg, H. Eggimann, M.-H. Liu, A. Varlet, M. Eich, P. Simonet, Y. Lee, K. Watanabe, T. Taniguchi, K. Richter, V. I. Fal'ko, K. Ensslin, and T. Ihn, “Oscillating magnetoresistance in graphene p-n junctions at intermediate magnetic fields”, arXiv:1612.07624
2. R. Pisoni, Y. Lee, H. Overweg, M. Eich, P. Simonet, K. Watanabe, T. Taniguchi, R. Gorbachev, T. Ihn, and K. Ensslin“Quantized conductance and broken symmetry states in MoS2 van der Waals heterostructures” , arXiv:1701.08619