Condensed matter: Cutting it fine

Appl. Phys. Lett. 96, 053107 (2010)

Atomically thin sheets of carbon called graphene are revered for their unusual electrical properties (see Journal Club). Now graphene has competition: Alexander Balandin and his colleagues at the University of California, Riverside, have found another material that can form atomically thin flakes, bismuth telluride (Bi₂Te₃).

Unlike graphene, which consists of layers just one atom thick, Bi₂Te₃ has five closely packed atomic sheets bound by weak forces. The researchers created flakes of five sheets or fewer by rubbing them off a larger crystal mechanically, a method similar to that used to isolate graphene. The flakes had different electrical properties depending on the number of atomic sheets they contained, which might allow Bi₂Te₃ sheets to be 'tuned' for different uses.

Moreover, Bi₂Te₃ can turn a heat gradient into an electrical current. This conversion, the authors suggest, might be more efficient in the graphene-like Bi₂Te₃ sheets than in their bulk crystal counterparts.