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首页> 外文期刊>Physical review >Excitonic and nematic instabilities on the surface of topological Kondo insulators
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Excitonic and nematic instabilities on the surface of topological Kondo insulators

机译：近藤拓扑绝缘子表面的激子和向列不稳定性

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摘要

We study the effects of strong electron-electron interactions on the surface of cubic topological Kondo insulators (such as samarium hexaboride, SmB_6). Cubic topological Kondo insulators generally support three copies of massless Dirac nodes on the surface, but only two of them are energetically degenerate and exhibit an energy offset relative to the third one. With a tunable chemical potential, when the surface states host electron and hole pockets of comparable size, strong interactions may drive this system into rotational symmetry breaking nematic and translational symmetric breaking excitonic spin- or charge-density-wave phases, depending on the relative chirality of the Dirac cones. Taking a realistic surface band structure into account we analyze the associated Ginzburg-Landau theory and compute the mean-field phase diagram for interacting surface states. Beyond mean-field theory, this system can be described by a two-component isotropic Ashkin-Teller model at finite temperature, and we outline the phase diagram of this model. Our theory provides a possible explanation of recent measurements which detect a twofold symmetric magnetoresistance and an upturn in surface resistivity with tunable gate voltage in SmB_6. Our discussion can also be germane to other cubic topological insulators, such as ytterbium hexaboride (YbB_6) and plutonium hexaboride (PuB_6).
机译：我们研究了强电子电子相互作用对立方拓扑近藤绝缘子（如六硼化sa，SmB_6）表面的影响。立方拓扑Kondo绝缘子通常在表面上支撑三个副本的无质量Dirac节点，但其中只有两个是能量退化的，并且相对于第三个节点表现出能量偏移。具有可调节的化学势，当表面态具有相当大小的电子和空穴时，强烈的相互作用可能使该系统旋转对称，破坏了向列相和平移对称，从而打破了激子自旋或电荷密度波相，这取决于相对手性狄拉克锥体。考虑到现实的表面带结构，我们分析了相关的Ginzburg-Landau理论，并计算了相互作用的表面状态的平均场相位图。除了平均场理论之外，该系统还可以用两组分各向同性的Ashkin-Teller模型在有限温度下描述，我们概述了该模型的相图。我们的理论为最近的测量提供了可能的解释，这些测量检测到对称的磁阻和SmB_6中可调栅极电压的表面电阻率上升。我们的讨论也可以与其他立方拓扑绝缘体密切相关，例如六硼化（YbB_6）和六硼化p（PuB_6）。

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  • 来源
    《Physical review》 |2015年第24期|245431.1-245431.9|共9页
  • 作者

    Bitan Roy; Johannes Hofmann; Valentin Stanev; Jay D. Sau; Victor Galitski;

  • 作者单位

    Condensed Matter Theory Center and Joint Quantum Institute, University of Maryland, College Park, Maryland 20742-4111, USA;

    Condensed Matter Theory Center and Joint Quantum Institute, University of Maryland, College Park, Maryland 20742-4111, USA;

    Condensed Matter Theory Center and Joint Quantum Institute, University of Maryland, College Park, Maryland 20742-4111, USA;

    Condensed Matter Theory Center and Joint Quantum Institute, University of Maryland, College Park, Maryland 20742-4111, USA;

    Condensed Matter Theory Center and Joint Quantum Institute, University of Maryland, College Park, Maryland 20742-4111, USA and School of Physics, Monash University, Melbourne, Victoria 3800, Australia;

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  • 正文语种 eng
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  • 关键词

    electron states at surfaces and interfaces; collective effects (bose effects, phase space filling, andrnexcitonic phase transitions);

    机译：表面和界面的电子态;集体效应（玻色效应;相空间填充和正激子相变）;

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