POLAR KERR EFFECTS AND MAGNETIC CIRCULAR-DICHROISM IN YBA2CU3O7-DELTAFILMS

We have performed high-sensitivity magneto-optical measurements using alternating fields of small amplitude. With this technique we measured both polar Kerr effects and magnetic circular dichroism in YBa2Cu3O7- delta films at photon energies between 1.2 eV and 2.7 eV. The detectio n of three correlated effects enabled us for the first time to the com plex Verdet constant of YBa2Cu3O7-delta and to make an internal-consis tency check. The temperature dependence of magnetic circular dichroism is linear at all investigated photon energies and we find no hints fo r a temperature dependence of paramagnetic type.