(p. D1) In the universe of office supplies, pencil lead — a mixture of graphite and clay, which does not include any lead — appears unexceptional beyond its ability to draw dark lines.
But 15 years ago, scientists discovered that a single sheet of graphite — a one-atom-thick layer of carbon atoms laid out in a honeycomb pattern — is a wonder. This ultrathin carbon, called graphene, is flexible and lighter than paper yet 200 times stronger than steel. It is also a good conductor of heat and electrical current.
Scientists imagined all of the remarkable things that graphene might be made into: transistors, sensors, novel materials. But after studying and cataloging its properties, scientists moved on to other problems. Practical uses have been slow to come, because part of what makes graphene alluring — its strength — also makes the material difficult to cut into precise shapes.
Last year, graphene burst back on the physics research scene when physicists at the Massachusetts Institute of Technology discovered that stacking two sheets of the material, twisted at a small angle between them, opened up a treasure box of strange phenomena. It started a new field: twistronics.
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(Note: the online version of the story has the date Oct. 30, 2019, and has the title “A Physics Magic Trick: Take 2 Sheets of Carbon and Twist.”)