论文标题
通过表面特异性非线性Terahertz光谱研究的钙钛矿氧化物界面处的低频声子
Low-frequency Phonon at Perovskite Oxide Interface Studied by Surface-specific Nonlinear Terahertz Spectroscopy
论文作者
论文摘要
低频集体激发经常发生在Terahertz或多纹期光谱区域中，在许多新型新兴现象中起着至关重要的作用。尽管进行了大量研究，但由于缺乏可行的实验技术，对界面的这种激发的检测仍然具有挑战性。在这里，我们表明可以使用表面特异性的非线性Terahertz光谱表征界面低频模式。该技术使用脉冲内差异频率混合（DFM）过程，可以将二阶光谱范围扩展到Terahertz范围。作为演示，成功测量了SRTIO3（001）的表面声子（001）。该表面极化源自氧气空位的过量或界面处的电荷转移。我们还开发了一种分析程序，用于在实用环境中远程测量复杂氧化物的界面潜力。我们的方法为广泛学科界面的低频激发的现场研究提供了新的机会。
The low-frequency collective excitations, which often occur in the terahertz or multi-terahertz spectral region, play an essential role in many novel emergent phenomena. Despite numerous studies in the bulk, detection of such excitations at interfaces remains challenging owing to the lack of feasible experimental techniques. Here, we show that interfacial low-frequency modes can be characterized using surface-specific nonlinear terahertz spectroscopy. This technique uses intra-pulse difference frequency mixing (DFM) process that can extend the second-order optical spectroscopy to the terahertz range. As a demonstration, the surface phonon of SrTiO3(001) at 2.8 THz was successfully measured. This surface polarization originates from the excess of oxygen vacancies or charge transfer at the interface. We have also developed an analytical procedure for remote measurement of the interfacial potential of complex oxides in a practical environment. Our method offers new opportunities for in situ studies of the low-frequency excitations at interfaces in broad disciplines.
