论文标题
AC测量低温下薄膜的Nernst效应
AC Measurement of the Nernst effect of thin films at low temperatures
论文作者
论文摘要
我们描述了一种交替的当前方法，用于测量低温下超导薄膜的Nernst效应。 Nernst效应是理解超导波动的重要工具，尤其是在关键点附近的涡流运动。但是，在大多数材料中，典型的实验设置中的NernST信号很少超过几美元$ V，在某些情况下，NV低至几个NV。此类小信号的直流测量需要广泛的信号处理和防止杂散拾取和偏移的保护，这将此类尺寸的敏感性限制在$> $ 5NV上。在这里，我们描述了一种利用单脚架两倍计设置的方法，并使用样品进行片上制造的加热元件和温度计，这有助于减少基板和温度计之间的热负载和温度滞后。使用AC加热功率和2 $ω$测量，我们能够在20-30nm Moge薄膜上在玻璃基板上实现亚纳诺夫的灵敏度，而使用同一设置上的DC技术的灵敏度为$ \ sim $ 9NV。
We describe an alternating current method to measure the Nernst effect in superconducting thin films at low temperatures. The Nernst effect is an important tool in the understanding superconducting fluctuations and, in particular, vortex motion near critical points. However, in most materials, the Nernst signal in a typical experimental setup rarely exceeds a few $μ$V, in some cases being as low as a few nV. DC measurements of such small signals require extensive signal processing and protection against stray pickups and offsets, limiting the sensitivity of such measurements to $>$5nV. Here we describe a method utilizing a one-heater-two-thermometer setup with the heating element and thermometers fabricated on-chip with the sample, which helped to reduce thermal load and temperature lag between the substrate and thermometer. Using AC heating power and 2$ω$ measurement, we are able to achieve sub-nanovolt sensitivity in 20-30nm MoGe thin films on glass substrate, compared to a sensitivity of $\sim$9nV using DC techniques on the same setup.
