Recipe Note: Three groups of creative chefs simultaneously developed this zesty recipe, each adding its own special techniques and flavoring. Here’s the basic recipe:
- Precool experimental chamber to -273 °C.
- Ramp up magnetic field to 35 teslas.
- 1 graphene flake
- 1 layer boron nitride
A beautiful fractal energy pattern and validation of a decades-old physics prediction.
- Gently place the graphene flake atop the boron nitride to create a lovely moiré pattern.
- Carefully place this combination inside the precooled, high-field experimental space.
- When your data reveals a fractional quantum Hall state, your sandwich is done and your data is ready to share with Science and Nature!
- Turn off the magnet to find that the graphene has become a semiconductor with a band gap — potentially useful as a transistor.
The Columbia University variation:
Hofstadter's butterfly and the fractal quantum Hall effect in moiré superlattices,, Nature, Vol. 497 (30 May 2013).
The Chefs: C.R. Dean, L. Wang, P. Maher, C. Forsythe, F. Ghahari, Y. Gao, J. Katoch, M. Ishigami, P. Moon, M. Koshino, T. Taniguchi, K. Watanabe, K. L. Shepard, J. Hone & P. Kim.
The University of Manchester variation:
Cloning of Dirac fermions in graphene superlattices,, Nature Vol. 497 (30 May 2013).
The Chefs: L.A. Ponomarenko, R.V. Gorbachev, G.L. Yu, D.C. Elias, R. Jalil, A.A. Patel, A. Mishchenko, A.S. Mayorov, C.R. Woods, J.R. Wallbank, M. Mucha-Kruczynski, B.A. Piot, M. Potemski, I.V. Grigorieva, K.S. Novoselov, F. Guinea, V. I. Fal'ko & A.K. Geim.
The MIT variation:
Massive Dirac Fermions and Hofstadter Butterfly in a van der Waals Heterostructure,, Science, Vol. 340, Issue 6139 (21 Jun 2013).
The Chefs: B. Hunt, J.D. Sanchez- Yamagishi, A.F. Young, M. Yankowitz, B.J. LeRoy, L. Watanabe, T. Taniguchi, P. Moon, M. Koshino, P. Jarillo- Herrero, R.C. Ashoori.