Direct Observation of the Linear Dichroism Transition in Two-Dimensional Palladium Diselenide
Direct Observation of the Linear Dichroism Transition in Two-Dimensional Palladium Diselenide
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二维二硒化钯中线性二色性跃迁的直接观察
DOI：
10.1021/acs.nanolett.9b04598
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发表时间：
2020
期刊：
影响因子：
10.8
通讯作者：
Liu Yanping
中科院分区：
文献类型：
--
作者：
Yu Juan;Kuang Xiaofei;Gao Yuanji;Wang Yunpeng;Chen Keqiu;Ding Zhongke;Liu Jia;Cong Chunxiao;He Jun;Liu Zongwen;Liu Yanping
各向异性光子材料的线性二色性跃迁在偏振波长选择探测器、光开关和光通信等领域具有广阔的应用前景。在传统的二维（2D）各向异性材料中，LD在广泛的波长范围内主要是单轴的，主要是由于材料的对称性降低而产生的。然而，晶体二维材料中的LD转变行为仍然是难以捉摸的。在这里，我们用偏振分辨吸收光谱证明了在波长为472 nm的二硒化钯（PdSe2）中观察到一种独特的LD转换现象。该材料具有明显的各向异性响应，αy/αx在364 nm处≈1.11，在532 nm处为1.15，在633 nm处为0.84。我们认为这种异常的LD转换行为源于该材料中存在的不同平行能带的强局域化规则。此外，偏振分辨拉曼光谱中Agand b1g模式的鲁棒周期性与理论结构对称性分析相吻合。这表明PdSe2的各向异性具有很强的本征LD效应，可以从宏观上确定晶体取向。这种独特的LD转换特性，加上强大的LD效应，使空气稳定的pdse2成为多光谱成像、传感、偏振敏感和波长可控光电子应用中技术创新的潜在候选者。
The linear dichroism (LD) transition within anisotropic photonic materials displays promising prospects for applications in polarization-wavelength-selective detectors, optical switching, and optical communication. In conventional two-dimensional (2D) anisotropic materials, the LD is predominantly uniaxial over a broad spectrum of wavelengths and arises principally from the reduced symmetry of the materials. However, the LD transition behavior in crystalline 2D materials remains elusive. Here, we demonstrate the observation of a unique LD conversion phenomenon at a wavelength of 472 nm in palladium diselenide (PdSe2) using polarization-resolved absorption spectroscopy. This material exhibits prominent anisotropic responses and a high absorption ratio of αy/αx≈ 1.11 at 364 nm, 1.15 at 532 nm, and 0.84 at 633 nm. We propose that this abnormal LD conversion behavior originates from the forceful localization rules at different parallel energy bands that exist within this material. Furthermore, the robust periodicity of Agand B1gmodes in polarization-resolved Raman spectroscopy is in good agreement with the theoretical structure symmetry analysis. This indicates the strong intrinsic LD effect in the anisotropic nature of PdSe2, which offers a macrolevel determination of crystal orientations. Such unique LD conversion features, in combination with strong LD effects, enable the air-stable PdSe2to be a potential candidate for technological innovations in multispectral imaging, sensing, and polarization-sensitive and wavelength-controllable photoelectronic applications.