Abstract:
The optical response to far infrared radiation has been measured on a mosaic of heavy
fermion CeCoIns single crystals. The superconducting transition temperature of the crystals
has been determined by van der Pauw resistivity and ac-susceptibility measurements
as Tc = 2.3 K. The optical measurements were taken above and below the transition
temperature using a ^He cryostat and step and integrate Martin-Puplett type polarizing
interferometer.
The absolute reflectance of the heavy fermion CeCoIns in the superconducting state
in range (0, 100)cm~^ was calculated from the measured thermal reflectance, using the
normal state data of Singley et al and a low frequency extrapolation for a metallic material
in the Hagen-Rubens regime. By means of Kramers-Kronig analysis the absolute
reflectance was used to calculate the optical conductivity of the sample.
The real part of the calculated complex conductivity a{u)) of CeCoIns indicates a
possible opening of an energy gap close to 50 cm~^.
