Unconventional valley-dependent optical selection rules and landau level mixing in bilayer graphene
Abstract
Selection rules are of vital importance in determining the basic optical properties of atoms, molecules and semiconductors. They provide general insights into the symmetry of the system and the nature of relevant electronic states. A two-dimensional electron gas in a magnetic field is a model system where optical transitions between Landau levels (LLs) are described by simple selection rules associated with the LL index N. Here we examine the inter-LL optical transitions of high-quality bilayer graphene by photocurrent spectroscopy measurement. We observed valley-dependent optical transitions that violate the conventional selection rules Δ|N| = ± 1. Moreover, we can tune the relative oscillator strength by tuning the bilayer graphene bandgap. Our findings provide insights into the interplay between magnetic field, band structure and many-body interactions in tunable semiconductor systems, and the experimental technique can be generalized to study symmetry-broken states and low energy magneto-optical properties of other nano and quantum materials.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Jun 10, 2020
- Source ID
- 10.1038/s41467-020-16844-y
Entities
People
- Dmitry Smirnov
- Erich J. Mueller
- Fan Zhang
- Farhan Rana
- Kenji Watanabe
- Lei Wang
- Long Ju
- Mykhaylo Ozerov
- Paul McEuen
- Seongphill Moon
- Takashi Taniguchi
- Xiao Li
- Zhengguang Lu
Organizations
- Air Force Office of Scientific Research
- National Science Foundation
- Office of Naval Research