发表机构
Indian Institute of Science Education and Research; University of Chemistry and Technology, Prague; University of Münster（印度科学教育与研究所; 布拉格化学技术大学; 明斯特大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究通过光谱与理论计算发现CrSBr具有极端光学带隙各向异性，是强偏振选择性激子系统，在偏振光电子学中具应用潜力。
AI 中文摘要
我们利用光吸收光谱和GW-贝特-萨尔彼特方程从头算计算，揭示了单层和类块体CrSBr中具有强各向异性的激子景观。通过直接吸收法确定最低亮光学起始态，即对应两个面内偏振本征轴的$X_0^a$和$X_0^b$激子，得到面内光学带隙各向异性为$470\ue00515$ meV，据我们所知，这是近红外至可见光谱范围内所有材料中观测到的最高值。在能量更高的区域，我们识别出多个沿两个正交轴选择性排列的强极化激子，能量范围为1.25 eV至3.1 eV。一个位于$X_0^b$下方24 meV的共振态$X^-$会逐渐将振子强度转移到$X_b^0$，该行为与耦合三激子（费米极化子）/激子对一致。我们的实验还提供了CrSBr的偏振分辨宽带介电函数。这些结果确立CrSBr为强偏振选择性的激子系统，并凸显其凭借大光学带隙各向异性在偏振选择性光电子学中的应用潜力。
英文摘要
We reveal a strongly anisotropic excitonic landscape in monolayer and bulk-like CrSBr using optical absorption spectroscopy and $GW$-Bethe-Salpeter equation $\textit{ab initio}$ calculations. The direct absorptive determination of the lowest bright optical onsets i.e. $X_0^a$ and $X_0^b$ excitons for the two in-plane polarization eigenaxes yield an in-plane optical gap anisotropy of $470 \pm 15$ meV. This is the highest observed value for any material in the near-infrared-to-visible spectral region to the best of our knowledge. Energetically above, we identify multiple strongly polarized excitons spanning $1.25$ eV to $3.1$ eV selectively aligned along the two orthogonal axes. A resonance $X^-$, located $24$ meV below the $X_0^b$ progressively transfers oscillator strength to $X_b^0$, a behavior consistent with a coupled trion (Fermi-polarion)/exciton pair. Our experiments also provide polarization-resolved broadband dielectric functions of CrSBr. These results establish CrSBr as a strongly polarization-selective excitonic system and highlight its potential for polarization-selective optoelectronics enabled with its large optical-gap anisotropy.
Comments15 pages, 4 figures in main text
