Disorder-enabled hydrodynamics of charge and heat transport in monolayer graphene
22 November 2018
Campus Groenenborger, Building U, Room 203 - Groenenborgerlaan 171 - 2020 Antwerpen
2:00 PM - 3:00 PM
Condensed Matter Theory Lecture presented by Dr Mohammad Zarenia
Contact email: firstname.lastname@example.org
Hydrodynamic behavior in electronic systems is commonly accepted to be associated with extremely clean samples such that electron-electron collisions dominate and total momentum is conserved. Contrary to this, we show that in monolayer graphene the presence of disorder is essential to enable an unconventional hydrodynamic regime which exists near the charge neutrality point and is characterized by a large enhancement of the Wiedemann-Franz ratio. Although the enhancement becomes more pronounced with decreasing disorder, the very possibility of observing the effect depends crucially on the presence of disorder. We calculate the maximum extrinsic carrier density n_c below which the effect becomes manifest, and show that n_c vanishes in the limit of zero disorder. We complete our analysis by presenting a transparent picture of the physical processes that are responsible for the crossover from conventional to disorder-enabled hydrodynamics. Recent experiments on monolayer graphene are discussed and shown to be consistent with this picture.