Many-body phase transitions found in suspended graphene multilayers!
Discovery of graphene—monolayer of graphite—has driven numerous developments in studies on atomically 'thin' 2D crystals where a rich variety of fascinating new phenomena has been observed. On the other hand, it has also provided another interesting research directions by enabling the isolation of arbitrary N -layers with well-preserved structural and electrical integrity. Taking advantage of such possibilities, we have studied transport properties of ultraclean suspended graphene multilayers and found that Bernal-stacked N -layer graphene exhibits finite-temperature phase transitions to many-body insulating states, surprisingly up to N =8 at temperatures as high as 100 K. These findings represent the first unambiguous experimental proof of the finite-temperature phase transitions solely driven by Coulomb interactions in low-dimensional systems, and clearly show that even the graphene layers as thick as N =8 behave quite differently from the graphite, the well-known se...