Yordanov Petar, Priessnitz Tim, Kim Min-Jae, Cristiani Georg, Logvenov Gennady, Keimer Bernhard, Kaiser Stefan
Max Planck Institute for Solid State Research, Heisenbergstraße 1, 70569, Stuttgart, Germany.
4th Physics Institute and Research Center SCoPE, University of Stuttgart, Pfaffenwaldring 57, 70569, Stuttgart, Germany.
Adv Mater. 2023 Oct;35(41):e2305622. doi: 10.1002/adma.202305622. Epub 2023 Sep 8.
Terahertz (THz) radiation is a powerful tool with widespread applications ranging from imaging, sensing, and broadband communications to spectroscopy and nonlinear control of materials. Future progress in THz technology depends on the development of efficient, structurally simple THz emitters that can be implemented in advanced miniaturized devices. Here, it is shown how the natural electronic anisotropy of layered conducting transition metal oxides enables the generation of intense terahertz radiation via the transverse thermoelectric effect. In thin films grown on off-cut substrates, femtosecond laser pulses generate ultrafast out-of-plane temperature gradients, which in turn launch in-plane thermoelectric currents, thus allowing efficient emission of the resulting THz field out of the film structure. This scheme is demonstrated in experiments on thin films of the layered metals PdCoO and La Sr CuO , and model calculations that elucidate the influence of the material parameters on the intensity and spectral characteristics of the emitted THz field are presented. Due to its simplicity, the method opens up a promising avenue for the development of highly versatile THz sources and integrable emitter elements.
太赫兹（THz）辐射是一种强大的工具，具有广泛的应用，涵盖成像、传感、宽带通信、光谱学以及材料的非线性控制等领域。太赫兹技术的未来发展取决于高效、结构简单的太赫兹发射器的开发，这些发射器可应用于先进的小型化设备中。在此，展示了层状导电过渡金属氧化物的自然电子各向异性如何通过横向热电效应产生强烈的太赫兹辐射。在偏离切割衬底上生长的薄膜中，飞秒激光脉冲产生超快的面外温度梯度，进而引发面内热电电流，从而使产生的太赫兹场能够有效地从薄膜结构中发射出来。该方案在层状金属PdCoO₂和La₂Sr₂CuO₄薄膜的实验中得到了验证，并给出了阐明材料参数对发射太赫兹场的强度和光谱特性影响的模型计算。由于其简单性，该方法为开发高度通用的太赫兹源和可集成发射极元件开辟了一条有前景的途径。
