An interesting in-plane anisotropic layered dimetal chalcogenide Ta₂NiS₅ is introduced, and the optical and electrical properties with respect to its in-plane anisotropy are systematically studied. The Raman vibration modes have been identified by Raman spectra measurements combined with calculations of phonon-related properties. Importantly, the Ta₂NiS₅ flakes exhibit strong anisotropic Raman response under the angle-resolved polarized Raman spectroscopy measurements. We found that Raman intensities of the A_g mode not only depend on rotation angle but are also related to the sample thickness. In contrast, the infrared absorption with light polarized along the a axis direction is always larger than that in the c axis direction regardless of thickness under the polarization-resolved infrared spectroscopy measurements. Remarkably, the first-principles calculations combined with angle-resolved conductance measurements indicate strong anisotropic conductivity of Ta₂NiS₅. Our results not only prove Ta₂NiS₅ is a promising in-plane anisotropic 2D material but also provide an interesting platform for future functionalized electronic devices.

中文翻译：

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层状双金属硫族化物中光和电响应的强平面各向异性

介绍了一种有趣的面内各向异性层状双金属硫属元素化物Ta ₂ NiS ₅，并且系统地研究了其各向异性的光学和电学性质。拉曼振动模式已通过拉曼光谱测量与声子相关特性的计算相结合来确定。重要的是，Ta ₂ NiS ₅薄片在角度分辨偏振拉曼光谱测量下显示出很强的各向异性拉曼响应。我们发现，A _g模式的拉曼强度不仅取决于旋转角度，而且还与样品厚度有关。相比之下，红外吸收的光沿a方向偏振不论偏振分辨红外光谱法测量的厚度如何，轴方向始终大于c轴方向。值得注意的是，第一性原理计算与角度分辨电导率测量相结合，显示出Ta ₂ NiS _5的强各向异性导电性。我们的结果不仅证明Ta ₂ NiS ₅是一种有前途的面内各向异性2D材料，而且还为将来的功能化电子设备提供了一个有趣的平台。