†Mackgraphe-Graphene and Nanomaterials Research Center, Mackenzie Presbyterian University, 01302-907 São Paulo, Brazil.
‡Departamento de Física, UFMG, 30123-970 Belo Horizonte, Brazil.
ACS Nano. 2015 Apr 28;9(4):4270-6. doi: 10.1021/acsnano.5b00698. Epub 2015 Mar 16.
Anisotropic materials are characterized by a unique optical response, which is highly polarization-dependent. Of particular interest are layered materials formed by the stacking of two-dimensional (2D) crystals that are naturally anisotropic in the direction perpendicular to the 2D planes. Black phosphorus (BP) is a stack of 2D phosphorene crystals and a highly anisotropic semiconductor with a direct band gap. We show that the angular dependence of polarized Raman spectra of BP is rather unusual and can be explained only by considering complex values for the Raman tensor elements. This result can be traced back to the electron-photon and electron-phonon interactions in this material.
各向异性材料的特点是具有独特的光学响应，这种响应高度依赖于偏振。特别有趣的是由二维（2D）晶体堆叠而成的层状材料，这些晶体在垂直于 2D 平面的方向上具有天然各向异性。黑磷（BP）是由二维磷烯晶体堆叠而成的，是一种具有直接带隙的各向异性半导体。我们表明，BP 的偏振拉曼光谱的角度依赖性相当不寻常，只能通过考虑拉曼张量元素的复数值来解释。这一结果可以追溯到该材料中的电子-光子和电子-声子相互作用。
