FAR-INFRARED MAGNETOOPTICS OF HIGH-T(C) SUPERCONDUCTORS

Measurements in polarized light have shown optical activity consistent with cyclotron resonance of the hole system in superconducting YBa2Cu 3O7 with a cyclotron mass of (3.1 +/- 0.5)m(e). The optical activity i s quenched at low frequencies (omega less than or similar to 40 cm-1). In unpolarized light a resonance is observed at omega congruent-to 65 cm-1 which is attributed to the vortex core resonance. This feature i s non-chiral. The results are compared with the optical conductivity b ased on a microscopic theory of vortex dynamics by T. Hsu. The theory successfully describes the optical activity but it cannot explain the magnitude or nonchirality of the vortex resonance. Possible mechanisms for the observed resonance are discussed.