  Here we report from our theoretical studies that in biased bilayer graphene,
one can induce phase transitions from an incompressible fractional quantum Hall
state to a compressible state by tuning the bandgap at a given electron
density. The nature of such phase transitions is different for weak and strong
inter-layer coupling. Although for strong coupling more levels interact there
are lesser number of transitions than for the weak coupling case. The
intriguing scenario of tunable phase transitions in the fractional quantum Hall
states is unique to bilayer graphene and never before existed in conventional
semiconductor systems.
