{"id":37964,"date":"2020-07-31T15:32:00","date_gmt":"2020-07-31T12:32:00","guid":{"rendered":"https:\/\/en.buradabiliyorum.com\/physicists-find-misaligned-carbon-sheets-yield-unparalleled-properties\/"},"modified":"2020-07-31T15:32:00","modified_gmt":"2020-07-31T12:32:00","slug":"physicists-find-misaligned-carbon-sheets-yield-unparalleled-properties","status":"publish","type":"post","link":"https:\/\/buradabiliyorum.com\/en\/physicists-find-misaligned-carbon-sheets-yield-unparalleled-properties\/","title":{"rendered":"#Physicists find misaligned carbon sheets yield unparalleled properties"},"content":{"rendered":"

“#Physicists find misaligned carbon sheets yield unparalleled properties<\/strong>”<\/p>\n

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\"Physicists<\/img>
\n Graphene is a single layer of carbon atoms arranged in a flat honeycomb pattern, where each hexagon is formed by six carbon atoms at its vertices. UT Dallas physicists are studying the electrical properties that emerge when two layers of graphene are stacked. Credit: University of Texas at Dallas
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A material composed of two one-atom-thick layers of carbon has grabbed the attention of physicists worldwide for its intriguing\u2014and potentially exploitable\u2014conductive properties.<\/p>\n

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Dr. Fan Zhang, assistant professor of physics in the School of Natural Science<\/a>s and Mathematics at The University of Texas at Dallas, and physics doctoral student Qiyue Wang published an article in June with Dr. Fengnian Xia’s group at Yale University in Nature Photonics<\/i> that describes how the ability of twisted bilayer graphene to conduct electrical current changes in response to mid-infrared light.<\/p>\n

From One to Two Layers<\/b>
\nGraphene is a single layer of carbon atoms arranged in a flat honeycomb pattern, where each hexagon is formed by six carbon atoms at its vertices. Since graphene’s first isolation in 2004, its unique properties have been intensely studied by scientists for potential use in advanced computers, materials and devices.
\nIf two sheets of graphene are stacked on top of one another, and one layer is rotated so that the layers are slightly out of alignment, the resulting physical configuration, called twisted bilayer graphene, yields electronic properties that differ significantly from those exhibited by a single layer alone or by two aligned layers.
\n“Graphene has been of interest for about 15 years,” Zhang said. “A single layer is interesting to study, but if we have two layers, their interaction should render much richer and more interesting physics. This is why we want to study bilayer graphene systems.”
\nA New Field Emerges<\/b>
\nWhen the graphene layers are misaligned, a new periodic design in the mesh emerges, called a moir\u00e9 pattern. The moir\u00e9 pattern is also a hexagon, but it can be made up of more than 10,000 carbon atoms.
\n“The angle at which the two layers of graphene are misaligned\u2014the twist angle\u2014is critically important to the material’s electronic properties,” Wang said. “The smaller the twist angle, the larger the moir\u00e9 periodicity.”
\nThe unusual effects of specific twist angles on electron behavior were first proposed in a 2011 article by Dr. Allan MacDonald, professor of physics at UT Austin, and Dr. Rafi Bistritzer. Zhang witnessed the birth of this field as a doctoral student in MacDonald’s group.<\/p>\n

“At that time, others really paid no attention to the theory, but now it has become arguably the hottest topic in physics,” Zhang said.
\nIn that 2011 research MacDonald and Bistritzer predicted that electrons’ kinetic energy can vanish in a graphene bilayer misaligned by the so-called “magic angle” of 1.1 degrees. In 2018, researchers at the Massachusetts Institute of Technology<\/a> proved this theory, finding that offsetting two graphene layers by 1.1 degrees produced a two-dimensional superconductor, a material that conducts electrical current with no resistance and no energy loss.<\/p>\n

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