Benyamini Avishai, Kennes Dante M, Telford Evan J, Watanabe Kenji, Taniguchi Takashi, Millis Andrew J, Hone James, Dean Cory R, Pasupathy Abhay N
Department of Mechanical Engineering, Columbia University, New York, New York 10027, United States.
Institut für Theorie der Statistischen Physik, RWTH Aachen University and JARA-Fundamentals of Future Information Technology, 52056 Aachen, Germany.
Nano Lett. 2021 Jan 13;21(1):583-589. doi: 10.1021/acs.nanolett.0c04024. Epub 2020 Dec 29.
Resistance in superconductors arises from the motion of vortices driven by flowing supercurrents or external electromagnetic fields and may be strongly affected by thermal or quantum fluctuations. The common expectation is that as the temperature is lowered, vortex motion is suppressed, leading to a decreased resistance. We show experimentally that in clean-limit atomically thin 2H-NbSe the resistance below the superconducting transition temperature may be nonmonotonic, passing through a minimum before increasing again as the temperature is decreased further. The effect is most pronounced in monolayer devices and cannot be understood in terms of known mechanisms. We propose a qualitative two-fluid vortex model in which thermal fluctuations of pinned vortices control the mobility of the free vortices. The findings provide a new perspective on fundamental questions of vortex mobility and dissipation in superconductors.
超导体中的电阻源于由流动的超电流或外部电磁场驱动的涡旋运动，并且可能受到热涨落或量子涨落的强烈影响。通常的预期是，随着温度降低，涡旋运动受到抑制，导致电阻减小。我们通过实验表明，在清洁极限的原子级薄2H-NbSe中，低于超导转变温度时电阻可能是非单调的，在温度进一步降低时先经过一个最小值然后再次增大。这种效应在单层器件中最为明显，并且无法用已知机制来解释。我们提出了一个定性的双流体涡旋模型，其中被钉扎涡旋的热涨落控制着自由涡旋的迁移率。这些发现为超导体中涡旋迁移率和耗散的基本问题提供了新的视角。
