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arXiv 2203.09083cond-mat.supr-con
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菱面体三层石墨烯中超导电性的泛函重整化群研究

Functional Renormalization Group Study of Superconductivity in Rhombohedral Trilayer Graphene

Wei Qin, Chunli Huang, Tobias Wolf, Nemin Wei, Igor Blinov, Allan H. MacDonald

AI总结:

本文利用泛函重整化群研究菱面体三层石墨烯的超导配对机制,发现排斥库仑相互作用借助环形费米海的动量空间结构诱导类d波自旋单态配对,理论相图与实验定性一致。

摘要:

我们采用泛函重整化群方法来确定在菱面体三层石墨烯中观测到的超导相的配对机制与对称性。该体系中的超导电性出现在载流子密度和位移场的一个区域,该区域具有弱畸变的环形费米海。我们发现,排斥性库仑相互作用可以利用与费米海环有限宽度相关的动量空间结构,在费米面上诱导电子配对。自旋单态与自旋三重态配对之间的简并被谷交换相互作用解除,这种相互作用在重整化群流下增强并发展出非平凡的动量空间结构。我们发现,主导的配对不稳定性是类$d$波且自旋单态的,并且理论得到的载流子密度-位移场相图与实验定性一致。

英文摘要:

We employ a functional renormalization group approach to ascertain the pairing mechanism and symmetry of the superconducting phase observed in rhombohedral trilayer graphene. Superconductivity in this system occurs in a regime of carrier density and displacement field with a weakly distorted annular Fermi sea. We find that repulsive Coulomb interactions can induce electron pairing on the Fermi surface by taking advantage of momentum-space structure associated with the finite width of the Fermi sea annulus. The degeneracy between spin-singlet and spin-triplet pairing is lifted by valley-exchange interactions that strengthen under the RG flow and develop nontrivial momentum-space structure. We find that the leading pairing instability is $d$-wave-like and spin-singlet, and that the theoretical phase diagram versus carrier density and displacement field agrees qualitatively with experiment.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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