Optical properties of RNi2B2C (R = Y, Lu, Ho, Er) intermetallic borocarbide superconductors

We have studied the optical properties of single crystals of RNi2B2C (R = Y, Lu, Er, Ho) intermetallic superconductors over a wide range of energies form 50 cm-1to 100000 cm- (6 meV to 12.4 eV) at room temperature by performing normal-incidence reflectivity measurements. The optical spectral functions of the four compounds show similar properties irrespective of the type of rare-earth ion or its magnetic moment. The optical conductivity of YNi2B2C at room temperature is reasonably well described by the simple Drude model for the electronic contribution and by six Lorentzian peaks representing interband transitions