查看完整版本: 石墨烯可能具有超流性能Graphene goes superfluid

石墨烯可能具有超流性能Graphene goes superfluid

[color=Blue][b]【纳米科技世界快讯】Graphene bilayers may show superfluidity – the flow of a fluid without resistance – at room temperature according to new calculations by researchers at the University of Texas. If confirmed in experiments, the material might be used to make low dissipation electronic devices in the future and even help extend Moore's law for another decade[/b][/color].
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K~S NCl"]B9E$Z Superfluidity appears in various systems, including conventional and high-temperature superconductors, and quantum hall bilayers. However, "dissipationless" flow is limited to very low temperatures – above a certain critical temperature, Tc, dissipation reappears.
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ze&S/{{\)] [color=DimGray]Normal to superuid phase diagram showing the dependence of the critical temperature Tc in Kelvin on the distance between layers d in nm and external bias electric field Eext in V/nm. Credit: H Min.[/color]T,iWvLS
For electronic applications, researchers would like to find materials with high Tc – such as superconductors that function at room temperature. This holy grail of superconductivity would revolutionize the way that most electrical devices work and may even bring about a second industrial revolution according to many physicists.
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"Our work suggests that a graphene bilayer will exhibit dissipationless flow at unprecedented high temperatures, which may even reach room temperature under certain experimental conditions," team member Hongki Min told nanotechweb.org.t7mcc%P

*Bg;dqE Q The researchers obtained their result using mean-field theory to estimate the critical temperature for dissipationless flow in two layers of graphene. They estimated the temperature at which unpaired vortices, which destroy the resistance-free flow at a critical "Kosterlitz-Thouless" temperature, form in the 2D system. The team found that this temperature can approach room temperature when the distance between the two layers is around 1 nm for a breakdown field of about 1 V/nm on a silicon dioxide substrate.0N9D,qo7y-\5ga0G

y5W-uiHPz8xn;r,R%P [b]Low-dissipation devices[/b]$is\k-O1u)}9m.A
The trend for electronic device development is to build low-dissipation devices, explained colleagues Rafi Bistritzer and Jung-Jung Su. If graphene bilayers can be engineered to perform under high enough temperatures, they may be able to extend Moore's law for another decade. This would be possible because the superfluidity in the material could enable dissipation-free interconnects and might allow for transistors that operate with a gate voltage much smaller than the thermal energy, kBT, thanks to the collective behaviour of many electrons. These devices would therefore use much less power.a$i.Q[q-Fg
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The team says that it now plans to further study high-temperature superfluidity in graphene bilayers, working closely with experimentalists to obtain a full understanding of this material."D e3H;B){'oW

Rt`W$qP?0P*k/x,k The work was reported in [url]www.arxiv.org/abs/0802.3462.[/url]
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-O|0oiG+U9\(q%d!\8X 来源： nanotechweb.org