Sternbach Aaron J, Ruta Francesco L, Shi Yin, Slusar Tetiana, Schalch Jacob, Duan Guangwu, McLeod Alexander S, Zhang Xin, Liu Mengkun, Millis Andrew J, Kim Hyun-Tak, Chen Long-Qing, Averitt Richard D, Basov D N
Department of Physics, Columbia University, New York, New York 10027, United States.
Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, United States.
Nano Lett. 2021 Nov 10;21(21):9052-9060. doi: 10.1021/acs.nanolett.1c02638. Epub 2021 Nov 1.
We investigate transient nanotextured heterogeneity in vanadium dioxide (VO) thin films during a light-induced insulator-to-metal transition (IMT). Time-resolved scanning near-field optical microscopy (Tr-SNOM) is used to study VO across a wide parameter space of infrared frequencies, picosecond time scales, and elevated steady-state temperatures with nanoscale spatial resolution. Room temperature, steady-state, phonon enhanced nano-optical contrast reveals preexisting "hidden" disorder. The observed contrast is associated with inequivalent twin domain structures. Upon thermal or optical initiation of the IMT, coexisting metallic and insulating regions are observed. Correlations between the transient and steady-state nano-optical textures reveal that heterogeneous nucleation is partially anchored to twin domain interfaces and grain boundaries. Ultrafast nanoscopic dynamics enable quantification of the growth rate and bound the nucleation rate. Finally, we deterministically anchor photoinduced nucleation to predefined nanoscopic regions by locally enhancing the electric field of pump radiation using nanoantennas and monitor the on-demand emergent metallicity in space and time.
我们研究了二氧化钒（VO）薄膜在光致绝缘体-金属转变（IMT）过程中的瞬态纳米纹理异质性。时间分辨扫描近场光学显微镜（Tr-SNOM）用于在红外频率、皮秒时间尺度和升高的稳态温度的广泛参数空间内，以纳米级空间分辨率研究VO。室温、稳态下，声子增强的纳米光学对比度揭示了预先存在的“隐藏”无序。观察到的对比度与不等价孪晶畴结构有关。在IMT的热或光引发时，观察到共存的金属和绝缘区域。瞬态和稳态纳米光学纹理之间的相关性表明，异质形核部分锚定在孪晶畴界面和晶界上。超快纳米动力学能够量化生长速率并限制形核速率。最后，我们通过使用纳米天线局部增强泵浦辐射的电场，将光致形核确定性地锚定到预定义的纳米区域，并监测空间和时间上按需出现的金属性。
