State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 200433, Shanghai, China.
Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, 200433, Shanghai, China.
Nat Commun. 2018 Nov 7;9(1):4656. doi: 10.1038/s41467-018-07123-y.
Quantum Griffiths singularity was theoretically proposed to interpret the phenomenon of divergent dynamical exponent in quantum phase transitions. It has been discovered experimentally in three-dimensional (3D) magnetic metal systems and two-dimensional (2D) superconductors. But, whether this state exists in lower dimensional systems remains elusive. Here, we report the signature of quantum Griffiths singularity state in quasi-one-dimensional (1D) TaPdS nanowires. The superconducting critical field shows a strong anisotropic behavior and a violation of the Pauli limit in a parallel magnetic field configuration. Current-voltage measurements exhibit hysteresis loops and a series of multiple voltage steps in transition to the normal state, indicating a quasi-1D nature of the superconductivity. Surprisingly, the nanowire undergoes a superconductor-metal transition when the magnetic field increases. Upon approaching the zero-temperature quantum critical point, the system uncovers the signature of the quantum Griffiths singularity state arising from enhanced quenched disorders, where the dynamical critical exponent becomes diverging rather than being constant.
量子 Griffiths 奇异点理论上被提出用于解释量子相变中发散动力学指数的现象。它已经在三维（3D）磁性金属系统和二维（2D）超导体中被实验发现。但是，这种状态是否存在于低维系统中仍然难以捉摸。在这里，我们报告了在准一维（1D）TaPdS 纳米线中存在量子 Griffiths 奇异点状态的特征。超导临界场在平行磁场配置中表现出强烈的各向异性行为和违反泡利极限。电流-电压测量在向正常状态转变时呈现滞后回线和一系列多个电压阶跃，表明超导性具有准一维性质。令人惊讶的是，当磁场增加时，纳米线会经历超导-金属转变。当接近零温量子临界点时，系统揭示了由增强的淬火无序引起的量子 Griffiths 奇异点状态的特征，其中动力学临界指数变得发散而不是常数。
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