• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Nature >Unconventional superconductivity in magic-angle graphene superlattices
【24h】

Unconventional superconductivity in magic-angle graphene superlattices

机译：魔角石墨烯超晶格中的非常规超导性

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The behaviour of strongly correlated materials, and in particular unconventional superconductors, has been studied extensively for decades, but is still not well understood. This lack of theoretical understanding has motivated the development of experimental techniques for studying such behaviour, such as using ultracold atom lattices to simulate quantum materials. Here we report the realization of intrinsic unconventional superconductivity-which cannot be explained by weak electron-phonon interactions-in a two-dimensional superlattice created by stacking two sheets of graphene that are twisted relative to each other by a small angle. For twist angles of about 1.1 degrees-the first 'magic' angle-the electronic band structure of this 'twisted bilayer graphene' exhibits flat bands near zero Fermi energy, resulting in correlated insulating states at half-filling. Upon electrostatic doping of the material away from these correlated insulating states, we observe tunable zero-resistance states with a critical temperature of up to 1.7 kelvin. The temperature-carrier-density phase diagram of twisted bilayer graphene is similar to that of copper oxides (or cuprates), and includes dome-shaped regions that correspond to superconductivity. Moreover, quantum oscillations in the longitudinal resistance of the material indicate the presence of small Fermi surfaces near the correlated insulating states, in analogy with underdoped cuprates. The relatively high superconducting critical temperature of twisted bilayer graphene, given such a small Fermi surface (which corresponds to a carrier density of about 1011 per square centimetre), puts it among the superconductors with the strongest pairing strength between electrons. Twisted bilayer graphene is a precisely tunable, purely carbon-based, two-dimensional superconductor. It is therefore an ideal material for investigations of strongly correlated phenomena, which could lead to insights into the physics of high-critical-temperature superconductors and quantum spin liquids.
机译：高度相关的材料，特别是非常规超导体的行为，已经进行了数十年的广泛研究，但仍未被很好地理解。缺乏理论上的理解促使了研究此类行为的实验技术的发展，例如使用超冷原子晶格来模拟量子材料。在这里，我们报告了一种固有的非常规超导电性的实现-无法通过弱的电子-声子相互作用来解释-在通过堆叠两张彼此相对的小角度扭曲的石墨烯而创建的二维超晶格中。对于约1.1度的扭曲角（第一个“魔术”角），此“双分子层石墨烯”的电子能带结构在接近费米能量的情况下显示出平坦的能带，从而在半填充时产生了相关的绝缘态。在材料远离这些相关的绝缘态进行静电掺杂后，我们观察到临界温度高达1.7开尔文的可调零电阻状态。扭曲的双层石墨烯的载流子密度相图类似于氧化铜（或铜酸盐），并且包括与超导性相对应的圆顶形区域。此外，材料的纵向电阻中的量子振荡表明，在相关的绝缘态附近存在小的费米表面，类似于掺杂不足的铜酸盐。在如此小的费米表面（对应于每平方厘米1010的载流子密度）的情况下，扭曲双层石墨烯的相对较高的超导临界温度使其成为电子之间的配对强度最强的超导体之一。扭曲的双层石墨烯是一种精确可调的，纯碳基的二维超导体。因此，它是研究强相关现象的理想材料，这可能导致对高临界温度超导体和量子自旋液体的物理学的深入了解。

著录项

  • 来源
    《Nature》 |2018年第7699期|43-50|共8页
  • 作者

    Cao Yuan; Fatemi Valla; Fang Shiang; Watanabe Kenji; Taniguchi Takashi; Kaxiras Efthimios; Jarillo-Herrero Pablo;

  • 作者单位

    MIT, Dept Phys, Cambridge, MA 02139 USA;

    MIT, Dept Phys, Cambridge, MA 02139 USA;

    Harvard Univ, Dept Phys, Cambridge, MA 02138 USA;

    Natl Inst Mat Sci, Namiki 1-1, Tsukuba, Ibaraki 3050044, Japan;

    Natl Inst Mat Sci, Namiki 1-1, Tsukuba, Ibaraki 3050044, Japan;

    Harvard Univ, Dept Phys, Cambridge, MA 02138 USA;

    MIT, Dept Phys, Cambridge, MA 02139 USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号