Direct Nanoscale Imagingof Ballistic and DiffusiveThermal Transport in Graphene Nanostructures.

We report direct imaging of nanoscale thermal transportin singleand few-layer graphene with approximately 50 nm lateral resolutionusing high vacuum scanning thermal microscopy. We observed increasedheat transport in suspended graphene where heat is conducted by ballisticphonons, compared to adjacent areas of supported graphene, and observeddecreasing thermal conductance of supported graphene with increasedlayer number. Our nanothermal images suggest a mean-free-path of thermalphonons in supported graphene below 100 nm. [ABSTRACT FROM AUTHOR]