Electronic structure and ultrafast dynamics of FeAs-based superconductors by angle- and timeresolved photoemission spectroscopy

点击翻译按钮获取中文摘要

This project is focused on the determination of the doping-dependent electronic structure of iron-pnictide and iron-chalcogenide-based high-Tc superconductors and their parent compounds. The band structure of these materials and in particular the Fermi surface of these multiband systems is a major ingredient for the understanding of superconductivity, since it is generally believed that the antiferromagnetic order of the parent compounds and superconductivity in the doped compounds is related to a nesting between hole-pockets in the centre and electron pockets at the boundary of the Brillouin zone. For these studies we use both high-resolution angle-resolved photoemission spectroscopy (ARPES) with variable photon energies (synchrotron radiation) and the complementary technique of femtosecond time-resolved ARPES. This unique combination provides direct access to the electronic structure and quasiparticle scattering dynamics below and above the Fermi level for holes and electrons, respectively. We intend to analyze the symmetry of the superconducting gap by measuring the anisotropy of the gap not only parallel but also perpendicular to the layers. In addition important complementary information on the coupling of the charge carriers to bosonic excitations (phonons, spin fluctuations) and electron-electron scattering can be derived in the frequency and time domain. This is essential for the understanding of the superconducting state. For these investigations a close collaboration with other experimental and theoretical groups within the priority program is anticipated. Our work is based on the availability of single crystals grown in other groups.