Liebmann Marcus, Bindel Jan Raphael, Pezzotta Mike, Becker Stefan, Muckel Florian, Johnsen Tjorven, Saunus Christian, Ast Christian R, Morgenstern Markus
II. Institute of Physics B and JARA-FIT, RWTH Aachen University, 52074 Aachen, Germany.
Max-Planck-Institut für Festkörperforschung, 70569 Stuttgart, Germany.
Rev Sci Instrum. 2017 Dec;88(12):123707. doi: 10.1063/1.4999555.
We present the design and calibration measurements of a scanning tunneling microscope setup in a He ultrahigh-vacuum cryostat operating at 400 mK with a hold time of 10 days. With 2.70 m in height and 4.70 m free space needed for assembly, the cryostat fits in a one-story lab building. The microscope features optical access, an xy table, in situ tip and sample exchange, and enough contacts to facilitate atomic force microscopy in tuning fork operation and simultaneous magneto-transport measurements on the sample. Hence, it enables scanning tunneling spectroscopy on microstructured samples which are tuned into preselected transport regimes. A superconducting magnet provides a perpendicular field of up to 14 T. The vertical noise of the scanning tunneling microscope amounts to 1 pm within a 700 Hz bandwidth. Tunneling spectroscopy using one superconducting electrode revealed an energy resolution of 120 μeV. Data on tip-sample Josephson contacts yield an even smaller feature size of 60 μeV, implying that the system operates close to the physical noise limit.
我们展示了一种扫描隧道显微镜装置的设计和校准测量结果，该装置置于一个在400 mK温度下运行、保持时间为10天的氦超高温真空低温恒温器中。该低温恒温器高度为2.70 m，组装所需自由空间为4.70 m，可放置在一层实验室建筑内。显微镜具有光学通道、xy工作台、原位针尖和样品交换功能，以及足够的接口，便于在音叉操作中进行原子力显微镜检查，并同时对样品进行磁输运测量。因此，它能够对微结构样品进行扫描隧道光谱分析，这些样品被调整到预选的输运状态。一个超导磁体可提供高达14 T的垂直磁场。扫描隧道显微镜的垂直噪声在700 Hz带宽内为1 pm。使用一个超导电极的隧道光谱分析显示能量分辨率为120 μeV。关于针尖 - 样品约瑟夫森接触的数据产生了更小的60 μeV特征尺寸，这意味着该系统接近物理噪声极限运行。
