A scanning probe microscope coupled with either femtosecond laser pulses or terahertz pulses holds great promise not only for observing ultrafast phenomena but also for fabricating desirable structures at the nanoscale. In this study, we demonstrate that a few-nanometer-scale phase change can be non-thermally stored on the Ge2Sb2Te5 surface by a laser-driven scanning tunneling microscope (STM). An atomically flat Ge2Sb2Te5 surface was irradiated with the optical near-field generated by introducing femtosecond laser pulses to the STM tip-sample junction. The STM topographic images showed that few-nanometer-scale mounds appeared after irradiation. In addition, tunneling conductance spectra showed that the bandgap increased by 0.2 eV in the area of 5 × 5 nm2. These indicate that the nanoscale crystal-to-amorphous phase change was induced by the STM-tip-induced near field. Our approach presented here offers an unprecedented increase in the recording density of optical storage devices and is, therefore, expected to facilitate the development of next-generation information technology.

中文翻译：

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光辅助扫描隧道显微镜光学近场诱导Ge2Sb2Te5薄膜纳米级相变

扫描探针显微镜与飞秒激光脉冲或太赫兹脉冲相结合，不仅对观察超快现象而且在纳米尺度上制造所需的结构都有很大的希望。在这项研究中，我们证明了几纳米级的相变可以通过激光驱动的扫描隧道显微镜 (STM) 非热存储在 Ge2Sb2Te5 表面上。原子级平坦的 Ge2Sb2Te5 表面被通过将飞秒激光脉冲引入 STM 尖端 - 样品结产生的光学近场照射。STM 地形图像显示，辐照后出现了几纳米级的土丘。此外，隧道电导光谱表明，在 5 × 5 nm2 区域带隙增加了 0.2 eV。这些表明纳米级晶体到非晶相变是由 STM 尖端诱导的近场诱导的。我们在此提出的方法在光存储设备的记录密度方面提供了前所未有的增加，因此有望促进下一代信息技术的发展。