Strong magnetophonon oscillations in extra-large graphene
journal contributionposted on 06.08.2019, 09:57 authored by P Kumaravadivel, Mark GreenawayMark Greenaway, D Perello, A Berdyugin, J Birkbeck, J Wengraf, S Liu, JH Edgar, AK Geim, L Eaves, R Krishna Kumar
Van der Waals materials and their heterostructures offer a versatile platform for studying a variety of quantum transport phenomena due to their unique crystalline properties and the exceptional ability in tuning their electronic spectrum. However, most experiments are limited to devices that have lateral dimensions of only a few micrometres. Here, we perform magnetotransport measurements on graphene/hexagonal boron-nitride Hall bars and show that wider devices reveal additional quantum effects. In devices wider than ten micrometres we observe distinct magnetoresistance oscillations that are caused by resonant scattering of Landau-quantised Dirac electrons by acoustic phonons in graphene. The study allows us to accurately determine graphene’s low energy phonon dispersion curves and shows that transverse acoustic modes cause most of phonon scattering. Our work highlights the crucial importance of device width when probing quantum effects and also demonstrates a precise, spectroscopic method for studying electron-phonon interactions in van der Waals heterostructures.
Engineering and Physical Sciences Research Council (EPSRC), Graphene Flagship, the Royal Society and Lloyd’s Register Foundation
Materials Engineering and Processing program of the National Science Foundation under the award number CMMI 1538127