Strong magnetophonon resonance induced triple G-mode splitting in graphene on graphite probed by micromagneto Raman spectroscopy
The resonance between the G-band phonon excitation and Landau level optical transitions in graphene has been systematically studied by micromagneto Raman mapping. In purely decoupled graphene regions on a graphite substrate, eight traces of anticrossing spectral features with G-mode peaks are observ...
| Main Authors: | , , , , , , , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
American Physical Society
2014
|
| Online Access: | http://hdl.handle.net/1721.1/88722 https://orcid.org/0000-0001-8492-2261 |
| Summary: | The resonance between the G-band phonon excitation and Landau level optical transitions in graphene has been systematically studied by micromagneto Raman mapping. In purely decoupled graphene regions on a graphite substrate, eight traces of anticrossing spectral features with G-mode peaks are observed as a function of magnetic fields up to 9 T, and these traces correspond to either symmetric or asymmetric Landau level transitions. Three distinct split peaks of the G mode, named G[subscript −], G[subscript i], and G[subscript +], are observed at the strong magnetophonon resonance condition corresponding to a magnetic field of ∼4.65 T. These three special modes are attributed to (i) the coupling between the G phonon and the magneto-optical transitions, which is responsible for G[subscript +] and G[subscript −] and can be well described by the two coupled mode model and (ii) the magnetic field-dependent oscillation of the G[subscript i] band, which is currently explained by the G band of graphite modified by the interaction with G[subscript +] and G[subscript −]. The pronounced interaction between Dirac fermions and phonons demonstrates a dramatically small Landau level width (∼1.3 meV), which is a signature of the ultrahigh quality graphene obtained on the surface of graphite. |
|---|