Levallois Julien, Nedoliuk Ievgeniia O, Crassee Iris, Kuzmenko Alexey B
Department of Quantum Matter Physics, University of Geneva, CH-1211 Geneva 4, Switzerland.
Rev Sci Instrum. 2015 Mar;86(3):033906. doi: 10.1063/1.4914846.
We describe a simple magneto-optical experiment and introduce a magneto-optical Kramers-Kronig analysis (MOKKA) that together allow extracting the complex dielectric function for left- and right-handed circular polarizations in a broad range of frequencies without actually generating circularly polarized light. The experiment consists of measuring reflectivity and Kerr rotation, or alternatively transmission and Faraday rotation, at normal incidence using only standard broadband polarizers without retarders or quarter-wave plates. In a common case, where the magneto-optical rotation is small (below ∼0.2 rad), a fast measurement protocol can be realized, where the polarizers are fixed at 45(∘) with respect to each other. Apart from the time-effectiveness, the advantage of this protocol is that it can be implemented at ultra-high magnetic fields and in other situations, where an in-situ polarizer rotation is difficult. Overall, the proposed technique can be regarded as a magneto-optical generalization of the conventional Kramers-Kronig analysis of reflectivity on bulk samples and the Kramers-Kronig constrained variational analysis of more complex types of spectral data. We demonstrate the application of this method to the textbook semimetals bismuth and graphite and also use it to obtain handedness-resolved magneto-absorption spectra of graphene on SiC.
我们描述了一个简单的磁光实验，并介绍了一种磁光克莱默斯-克勒尼希分析方法（MOKKA），这两者共同使得在无需实际产生圆偏振光的情况下，能够在很宽的频率范围内提取左旋和右旋圆偏振的复介电函数。该实验包括在正入射时仅使用标准宽带偏振器（不使用延迟器或四分之一波片）来测量反射率和克尔旋转，或者测量透射率和法拉第旋转。在磁光旋转较小（低于约0.2弧度）的常见情况下，可以实现一种快速测量方案，其中偏振器相互固定在45度角。除了具有时间效率外，该方案的优点还在于它可以在超高磁场以及原位偏振器旋转困难的其他情况下实施。总体而言，所提出的技术可被视为对块状样品反射率的传统克莱默斯-克勒尼希分析以及对更复杂类型光谱数据的克莱默斯-克勒尼希约束变分分析的磁光推广。我们展示了该方法在教科书式半金属铋和石墨上的应用，还利用它获得了碳化硅上石墨烯的手性分辨磁吸收光谱。
