Energy spectrum of Eu localized states in the PbEuTe solid solution in the middle and far infrared region

在该项目中，我们希望进一步了解为什么稀土离子在半导体基质中形成局域态，特别是我们对与稀土离子低能谱相对应的弱相互作用感兴趣。的调查进行高品质的离子PbEuTe固溶体的外延层。这是PbTe窄隙半导体和EuTe宽隙反铁磁半导体的混合物，这具有重要的实际意义。在光学实验中，定域态被看作是离散的或多或少的窄线，表明地球与晶体环境的相互作用。我们想解释这些线是如何产生的，以及哪些相互作用决定了它们的光谱性质;此外，我们还利用它们来研究固体的特殊性质。特别重要的是p-d导带杂化，f -和d-电子的晶体场和自旋轨道相互作用，s-f，p-f和d-f交换相互作用。这些相互作用的量级为1 - 200 meV，对应于10 - 2x 103 cm-1的频率。因此，我们利用太赫兹和红外光谱的透射，反射和发光实验。为了避免特定的声子吸收区或移动衬底的Reststrahlen区，我们在不同的衬底（BaF 2，KCl，Si）上生长外延层。

In the project we want to advance the understanding why rare earth ions form localized states in a semiconductor matrix, in particular we are interested in weak interactions that corresponds to the low-energy spectrum of the rare earth ions. The investigations are performed on high-quality epitaxial layers of ionic PbEuTe solid solution. This is a mixture of the PbTe narrow-gap semiconductor and the EuTe wide-gap antiferromagnetic semiconductor, which is of significant practical interest. In optical experiments, localized states are seen as discrete more-or-less narrow lines that indicate the rear-earth interaction with the crystal environment. We want to explain how these lines arise and which interactions determine their spectral properties; in addition, we utilize them to investigate particular properties of solids. Of particular importance are the p-d conduction-bands hybridization, the crystal-field and spin-orbit interactions of both f - and d-electrons, the s-f, p-f and d-f exchange interactions. The magnitude of these interactions has the order of 1 - 200 meV that corresponds to frequencies of 10 - 2x103 cm-1. Hence, we utilize THz and infrared spectroscopy for transmission, reflection and luminescence experiments. In order to avoid the specific phonon absorption region or to shift the Reststrahlen region of the substrates, we grow epitaxial layers on different substrates (BaF2, KCl, Si).