Fabrication of mesoscopic devices from graphite microdisks

Structural and transport properties of individual micron-sized graphitic di sks with less than one hundred graphene layers are measured. Mesoscopic dev ices of any arbitrary geometry can be fabricated at the center of such disk s by focussed ion beam lithography, with the rest of the disk serving as lo w-resistance contacts. Our approach is exemplified by the fabrication and c haracterization of 30 to 60 nm wide point-contact devices. A size effect is revealed by the suppression of the magnetoresistance in constrictions narr ower than the smallest attained cyclotron orbit for fields up to 10 T. (C) 2001 American Institute of Physics.