Optical properties of organic superconductor kappa-(BETS)2 iron(IV) bromide.

摘要

kappa-(BETS)2FeBr4 is the first antiferromagnetic organic superconductor with successive antiferromagnetic and superconducting transitions at TN=2.5K and Tc=1.1K respectively at ambient pressure. Polarized reflectance measurements were performed on three single crystal-samples of this material using a Bruker IFS66V/S Interferometer, and a Bolometer detector or an MCT detector, at seven temperatures between 4K and 300K, in both the far-infrared and mid-infrared frequency range.;After the reflectance results were obtained, the Kramers-Kronig dispersion relation was applied to determine the optical conductivity of kappa-(BETS) 2FeBr4 at these seven temperatures. Additionally, the optical conductivity spectra were fitted with a Drude/Lorentz Oscillator model in order to study the evolution of the optical conductivity with temperature along the a-axis and c-axis. The resistivities calculated from the Drude model parameters along the a-axis and c-axis agreed reasonably with previous transport measurements.