Subcycle Mid-Infrared Electric-Field-Driven Scanning Tunneling Microscopy with a Time Resolution Higher Than 30 fs
Subcycle Mid-Infrared Electric-Field-Driven Scanning Tunneling Microscopy with a Time Resolution Higher Than 30 fs
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DOI：
10.1021/acsphotonics.2c00995
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发表时间：
2022-09-02
期刊：
影响因子：
7
通讯作者：
Shigekawa, Hidemi
中科院分区：
文献类型：
--
作者：
Arashida, Yusuke;Mogi, Hiroyuki;Shigekawa, Hidemi
使用太赫兹区域载波包络相控脉冲（THz-STM）的电场驱动扫描隧道显微镜（STM）因其探测材料中超快动力学的能力而引起了广泛关注。然而，由于电场处于太赫兹区域，其约1 ps的时间分辨率限制了可测量目标的范围。因此，为了研究凝聚态材料中基元激发和相变等非平衡态的局域动力学，需要开发具有更高时间分辨率的STM系统。在这里，我们报告了一种中红外（MIR）电场驱动的STM系统，使原子级泵浦探针方法能够在很宽的时间范围内使用，时间分辨率高于30 fs。我们通过可视化 MoTe2 中光致超快非平衡动力学，展示了新型 MIR-STM 系统的巨大潜力。我们成功地测量了 0 到超过 1 ps 时间范围内的超快载流子动力学，这可以通过与载流子动力学相关的能带结构的变化得到很好的解释。除了时间分辨信号测量之外，还实现了原子分辨的 MIR-STM 成像。
Electric-field-driven scanning tunneling microscopy (STM) that uses carrier envelope phase-controlled pulses in the THz region (THz-STM) has been attracting considerable attention because of its capability of probing ultrafast dynamics in materials. However, since the electric field is in the THz region, its time resolution of about 1 ps limits the range of measurable targets. Therefore, to pave the way for studying the local dynamics of non-equilibrium states such as elementary excitations and phase transitions in condensed materials, it is desirable to develop an STM system with a higher time resolution. Here, we report a mid-infrared (MIR) electric-field-driven STM system enabling an atomic-scale pump-probe method to be used over a wide range of time with a time resolution higher than 30 fs. We demonstrate the high potential of the new MIR-STM system by visualizing the photo-induced ultrafast non-equilibrium dynamics in MoTe2. We succeeded in measuring ultrafast carrier dynamics in the time range of 0 to over 1 ps, which were well explained by the change in band structure associated with the carrier dynamics. In addition to time-resolved signal measurement, atomically resolved MIR-STM imaging was also realized.