SCIENTISTS have long known that graphite is made of stacked sheets graphene, but they did not know how to look at a single sheet.

In 2004, two physicists at the University of Manchester in England, Andre Geim and Konstantin Noveselov, came up with decidedly low-tech method to produce it.

They used sticky tape - the same as you buy at an office supply store - to pull apart graphene layers until only one graphene layer was left.

In laboratories across the world, physicists rushed out to buy their own rolls of tape and pull apart slices of graphene.

Dr. Geim and Dr. Novoselov were honored with the 2010 Nobel Prize in Physics. But after a few years, scientists had figured out what they could and moved on.

''Until last year, graphene was slowly becoming out of fashion,'' said Pablo Jarillo-Herrero, a physicist at the Massachusetts Institute of Technology.

Still, some people like Allan H. MacDonald, a theoretical physicist at the University of Texas, thought that graphene mysteries had yet to be fully plumbed.

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.

The ultrathin carbon, called graphene, is flexible and lighter than paper yet 200 times as strong as 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

A paper published last week in the journal Nature takes the most detailed look at at the material, known as magic-angle twisted bilayer graphene.

The international team of scientists carried out a series of experiments and showed that tweaking graphene's temperature, magnetic field and the number of electrons able to move freely, shifted the material from behaving like an insulator, where electrical current foes not flow, to becoming a semiconductor, able to convey current without resistance.

The hope of twistronics is that researchers will be able to take advantage of the superconductivity and other properties to engineer novel electronics for quantum computers and other uses yet to be imagined.

''Our work really sort of shows the richness of the whole system, where we observe all of these effects at once,'' said Dmitri K. Efetov, a physicist at the Institute of Photonic Sciences and the Barcelona Institute of Science and Technology in Spain and the senior author of the paper.

The ability to easily nudge graphene into different types of behavior gives scientist a simple system to explore, as they try to understand the underlying physics of the superconducting activity, as well as other behaviors.

''He's the guy who's done this the best,'' Andrea Young, a physics professor at the University of California, Santa Barbara, who was not involved in the research, said of Dr. Efetov and his collaborators.
''Somehow they have the magic touch.''

Dr. Young said he and others were still sorting out what is going on in magic-angle twisted bilayer graphene.

''There's a lot of things that could happen, and which one does happen depends on a lot of experimental details,'' he said.

 The honor and serving of the latest global operational research on new materials and breakthroughs, continues. The World Students Society thanks author Kenneth Chang.


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