Strong magnetophonon oscillations induced by Dirac fermion - transverse acoustic phonon scattering in graphene

Two dimensional electron gas systems exhibit a plethora of quantum phenomena. Graphene has not only provided a versatile platform for studying many of these phenomena but also revealed new effects. However one of the first discoveries in quantum transport, well known for fifty years has remained conspicuously absent in graphene : magnetophonon oscillations. Here we present our recent work on magnetotransport in boron nitride encapsulated graphene devices of different widths [1] and show that the magnetoresistance of wider graphene devices reveal this hitherto elusive quantum phenomenon. In devices of channel width greater than ten micrometres we observe pronounced magnetophonon oscillations caused by resonant scattering of Landau quantised Dirac quasiparticles with acoustic phonons in graphene. Using this we determine graphene’s low energy phonon dispersion and also find that transverse acoustic modes are the dominant source of phonon scattering. The results highlight the importance of device size in studying new quantum phenomena and demonstrates a spectroscopic technique for studying the nature of electron-phonon interactions in van der Waals heterostructures.
[1] Kumaravadivel, P. et al. Strong magnetophonon oscillations in extra-large graphene. Nat Commun 10, 3334,