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arXiv 2302.13841cond-mat.str-el
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用于描述扭转WSe₂双层的莫尔$t$-$J$-$U$模型中的单重态-三重态混合超导态

Mixed singlet-triplet superconducting state within the moiré $t$-$J$-$U$ model as applied to the description of twisted WSe$_2$ bilayer

M. Zegrodnik, A. Biborski

AI总结:

该研究用Gutzwiller与Hartree-Fock方法分析扭转WSe₂双层莫尔平带的$t$-$J$-$U$模型,重现Mott绝缘态两侧双超导穹顶,并揭示栅压可调的$d+id$单重态与$p-ip$三重态混合配对。

摘要:

我们分析了一个$t$-$J$-$U$模型的类比形式,并将其应用于描述扭转WSe₂双层的单个莫尔平带。为了考虑由显著库仑排斥强度引起的关联效应,我们采用Gutzwiller方法,并将其与Hartree-Fock方法所得结果进行比较。我们详细讨论了通过系统增大库仑排斥积分$U$,超导态在相图中逐渐出现的双穹顶结构。位于Mott绝缘态两侧的两个超导穹顶可在符合现有实验数据的现实参数范围内重现。根据我们的分析,配对态具有高度非常规的特征,具有混合的$d+id$(单重态)和$p-ip$(三重态)对称性。混合配对态的两个分量具有相近的振幅。然而,如本文所示,通过调节控制体系中依赖谷的自旋劈裂大小的栅极电压,在所考虑的体系中实现纯单重态配对与纯三重态配对之间的转变应当是可能的。

英文摘要:

We analyze an analog of the $t$-$J$-$U$ model as applied to the description of a single moiré flat band of twisted WSe$_2$ bilayer. To take into account the correlation effects induced by a significant strength of the Coulomb repulsion, we use the Gutzwiller approach and compare it with the results obtained by the Hartree-Fock method. We discuss in detail the graduate appearance of a two dome structure of the superconducting state in the phase diagram by systematically increasing the Coulomb repulsion integral, $U$. The two superconducting domes residing on both sides of a Mott insulating state can be reproduced for a realistic parameter range in agreement with the available experimental data. According to our analysis the paired state has a highly unconventional character with a mixed $d+id$ (singlet) and $p-ip$ (triplet) symmetry. Both components of the mixed paired state are of comparable amplitudes. However, as shown here, a transition between pure singlet and pure triplet pairing should be possible in the considered system by tuning the gate voltage, which controls the magnitude of the valley-dependent spin-splitting in the system.

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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