Raman investigation of Fe-based chalcogenide films

Abstract

Micro-Raman spectroscopy of FeTe and superconductor Fe(SeTe) films was used to investigate the compression of the lattice which is a typical feature of chalcogenide films. The lattice strain has a strong influence on their electrical, magnetic and superconductor properties. In cases where spin-orbit coupling is non-negligible, an energy split of the 3d orbitals of the Fe atoms that removes the spin energy degeneracy could be generated. This leads to unconventional light scattering mechanisms involving single-magnon excitation. For this reason, we conducted a thorough investigation of FeTe and superconductor Fe(SeTe) films by using visible micro-Raman spectroscopy over a large temperature range. The Raman band at about 1520 cm−1 featured by the FeSe0.5Te0.5 films was assigned to the single-magnon scattering, while the Raman response of FeTe films was ascribed to more conventional two-magnon scattering mechanisms. The temperature dependence of the single-magnon Raman scattering was investigated in the temperature range from 15 K to 295 K, enabling information to be obtained on the influence of spin fluctuations on the magnetic order.