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arXiv 2205.07397cond-mat.supr-concond-mat.str-el
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非局域库仑作用驱动的Sn/Si(111)拓扑超导电性

Topological Superconductivity in Sn/Si(111) driven by non-local Coulomb interactions

Mehdi Biderang, Mohammad-Hossein Zare, Jesko Sirker

摘要:

最近在掺硼的($\sqrt{3}\times\sqrt{3}$)Sn/Si(111)中观察到了超导电性。该材料可以用三角格子上的扩展哈伯德模型来描述。在这里,我们使用的随机相位近似调查的电荷和自旋的波动,以及超导性能的系统相对于填充和相对强度的扩展与现场哈伯德相互作用。计算结果表明,在半填充和弱的扩展Hubbard相互作用下,超导基态呈现手征$d$波配对。远离半填充和较强的最近邻库仑相互作用,系统显示手性$p$波(空穴掺杂)和$f$波(电子掺杂)配对。对对称性对扩展Hubbard相互作用的依赖性表明,电荷涨落在库珀对的形成中起着重要作用。最后,计算了所有观察到的超导织构的Knight位移随温度的变化,并提出了一种检验超导能隙函数对称性的实验方法。

英文摘要:

Superconductivity was recently observed in boron-doped ($\sqrt{3}\times\sqrt{3}$)Sn/Si(111). The material can be described by an extended Hubbard model on a triangular lattice. Here, we use the random-phase approximation to investigate the charge and spin fluctuations as well as the superconducting properties of the system with respect to filling and the relative strength of the extended versus the on-site Hubbard interactions. Our calculations reveal that near half-filling and weak extended Hubbard interactions, the superconducting ground state exhibits chiral $d$-wave pairing. Far from half-filling and for stronger nearest-neighbor Coulomb interactions, the system shows chiral $p$-wave (hole-doping) and $f$-wave (electron-doping) pairings. The dependence of the pairing symmetry on the extended Hubbard interactions suggests that charge fluctuations play an important role in the formation of Cooper pairs. Finally, the temperature dependence of the Knight shift is calculated for all observed superconducting textures and put forward as an experimental method to examine the symmetry of the superconducting gap function.

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