Enhanced superconductivity in spin–orbit proximitized bilayer graphene
Enhanced superconductivity in spin–orbit proximitized bilayer graphene
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DOI：
10.1038/s41586-022-05446-x
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发表时间：
2022-05
期刊：
影响因子：
64.8
通讯作者：
Yiran Zhang;R. Polski;A. Thomson;É. Lantagne-Hurtubise;C. Lewandowski;Haoxin Zhou;Kenji Watanabe;T. Taniguchi;J. Alicea;S. Nadj-Perge
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文献类型：
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作者：
Yiran Zhang;R. Polski;A. Thomson;É. Lantagne-Hurtubise;C. Lewandowski;Haoxin Zhou;Kenji Watanabe;T. Taniguchi;J. Alicea;S. Nadj-Perge
在一个大的垂直电场的存在下，伯纳堆叠双层石墨烯（BLG）具有几个不对称金属相，以及磁场诱导的超导性。然而，超导态是相当脆弱的，只出现在一个狭窄的密度窗口和最高临界温度（c≈30 mK）。在这里，我们表明，将单层二硒化钨（WSe2）放置在BLG上，可以极大地促进库珀配对：超导性在零磁场下出现，在密度范围内表现出一个数量级的增强，并且密度范围扩大了8倍。通过将blg - wse2中的量子振荡映射为电场和掺杂的函数，我们确定超导性出现在正常状态极化的区域，其中四种自旋谷中的两种主要存在。面内磁场测量进一步表明，blg - wse2中的超导性可以表现出对掺杂临界场的显著依赖，超导圆顶的一端大致遵守钱德拉塞卡-克罗格斯顿（泡利）极限，而另一端则严重违反。此外，只有当垂直电场将BLG空穴波函数推向WSe2时才会出现超导性，这表明邻近诱导（Ising）自旋轨道耦合在稳定配对中起着关键作用。我们的研究结果为设计坚固、高度可调和超清洁的石墨烯超导体铺平了道路。
In the presence of a large perpendicular electric field, Bernal-stacked bilayer graphene (BLG) features several broken-symmetry metallic phases, –as well as magnetic-field-induced superconductivity. The superconducting state is quite fragile, however, appearing only in a narrow window of density and with a maximum critical temperatureTc≈ 30 mK. Here we show that placing monolayer tungsten diselenide (WSe2) on BLG promotes Cooper pairing to an extraordinary degree: superconductivity appears at zero magnetic field, exhibits an order of magnitude enhancement inTcand occurs over a density range that is wider by a factor of eight. By mapping quantum oscillations in BLG–WSe2as a function of electric field and doping, we establish that superconductivity emerges throughout a region for which the normal state is polarized, with two out of four spin-valley flavours predominantly populated. In-plane magnetic field measurements further reveal that superconductivity in BLG–WSe2can exhibit striking dependence of the critical field on doping, with the Chandrasekhar–Clogston (Pauli) limit roughly obeyed on one end of the superconducting dome, yet sharply violated on the other. Moreover, the superconductivity arises only for perpendicular electric fields that push BLG hole wavefunctions towards WSe2, indicating that proximity-induced (Ising) spin–orbit coupling plays a key role in stabilizing the pairing. Our results pave the way for engineering robust, highly tunable and ultra-clean graphene-based superconductors.