双轴应变调控的超导体在高达60 T脉冲磁场中的Shubnikov-de Haas振荡
Shubnikov-de Haas oscillations of biaxial-strain-tuned superconductors in pulsed magnetic field up to 60 T
AI总结：
本文通过双轴应变调控两种准二维超导体MoTe₂和RbV₃Sb₅，在60 T脉冲磁场下观测Shubnikov-de Haas振荡，发现应变可提高超导临界温度并增强有效质量，为极端条件下研究二维材料提供了新途径。
摘要：
二维（2D）材料不仅在基础研究中日益重要，在日常应用中也越来越突出。然而，要充分发挥其潜力，关键是要利用外部参数优化其性能，并同时追踪电子结构。宽磁场范围内的磁输运是探测电子结构的有力方法，对于金属性二维材料，叠加在输运信号上的量子振荡编码了费米面参数。在本文中，我们利用双轴应变作为外部调控参数，通过测量两种准二维超导体MoTe$_2$和RbV$_3$Sb$_5$在高达60 T的脉冲磁场中的磁电阻，研究了应变对其电子性质的影响。通过精心选择绝缘衬底，我们展示了分别对MoTe$_2$和RbV$_3$Sb$_5$施加压缩和拉伸双轴应变的可行性。对于这两个体系，施加的应变都使其超导临界温度相对于自由状态对应物有所提高，证明了这种双轴应变方法在低温下的有效性。在两个样品中都获得了磁电阻中清晰的量子振荡——即Shubnikov-de Haas（SdH）效应。在应变MoTe$_2$中，磁电阻表现出对磁场近乎二次方的依赖关系，即使在最高磁场下也保持不饱和。而在应变RbV$_3$Sb$_5$中，两个SdH频率的有效质量值显著增大，暗示电荷涨落可能增强。我们的结果表明，将双轴应变与脉冲磁场相结合，为在前所未有的条件下研究二维材料开辟了道路。
英文摘要：
Two-dimensional (2D) materials have gained increasing prominence not only in fundamental research but also in daily applications. However, to fully harness their potential, it is crucial to optimize their properties with an external parameter and track the electronic structure simultaneously. Magnetotransport over a wide magnetic field range is a powerful method to probe the electronic structure and, for metallic 2D materials, quantum oscillations superimposed on the transport signals encode Fermi surface parameters. In this manuscript, we utilize biaxial strain as an external tuning parameter and investigate the effects of strain on the electronic properties of two quasi-2D superconductors, MoTe$_2$ and RbV$_3$Sb$_5$, by measuring their magnetoresistance in pulsed magnetic fields up to 60 T. With a careful selection of insulating substrates, we demonstrate the possibility of both the compressive and tensile biaxial strain, imposed on MoTe$_2$ and RbV$_3$Sb$_5$, respectively. For both systems, the applied strain has led to superconducting critical temperature enhancement compared to their free-standing counterparts, proving the effectiveness of this biaxial strain method at cryogenic temperatures. Clear quantum oscillations in the magnetoresistance -- the Shubnikov-de Haas (SdH) effect -- are obtained in both samples. In strained MoTe$_2$, the magnetoresistance exhibits a nearly quadratic dependence on the magnetic field and remains non-saturating even at the highest field. Whereas in strained RbV$_3$Sb$_5$, two SdH frequencies showed a substantial enhancement in effective mass values, hinting at a possible enhancement of charge fluctuations. Our results demonstrate that combining biaxial strain and pulsed magnetic field paves the way for studying 2D materials under unprecedented conditions.
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