Far-infrared magnetotransmission measurements of normal-state thin films are discussed. The magneto-optical signals observed in circularly polarized light are consistent with the ac Hall effect of holes with a reduced scattering rate and an enhanced mass compared to the zero-field transport parameters. The results agree with a simple high-frequency extension of models which have been developed to explain the anomalous dc Hall effect in the normal state of high- superconductors in terms of two scattering rates. The Hall scattering rate , where and K. These experiments provide new tests of the Fermi-liquid versus non-Fermi-liquid nature of these materials.

The magneto-optical activity of superconducting YBa2Cu3O7 observed by Karrai et al. is not present in many commonly employed models of vortex dynamics. Here we propose a simple, unifying picture for the frequency dependent magneto-optic response of type-II superconductors at low temperatures. We bring together Kohn's theorem, vortex core excitations, and vortex pinning and damping into a single expression for the conductivity tensor. The theory describes magneto-optical activity observed in infrared transmission measurements of thin films of YBa2Cu3O7.PACS numbers: 74.25. Nf, 74.60.Ge, 74.25.Gz, 76.40.+b For applications of superconductivity vortex motion and pinning is of great importance. Many models for vortex dynamics have been developed such as those of Bardeen and Stephen [1], Nozieres and Vinen [2], and Clem and Coffey [3]. One way of studying vortex dynamics is to go to frequencies that are large compared with the characteristic frequencies associated with pinning and damping to observe the free inertial response of the vortices. This regime is not well studied and moreover a microscopic approach is needed. We note that, for high temperature superconductors, estimates [4] of the frequency range over which one expects electromagnetic absorption (10 10 − 10 14 s −1 ) overlaps with the microscopic energy scale associated with quantized quasiparticle states in vortex cores [5]. Because of the short coherence length in high temperature superconductors, the energy scale of quasi-particle states localized at the vortex core is large.These considerations have prompted a re-examination of vortex core states. Karrai et al. examined the magnetic field and frequency dependent infrared transmission coefficient of thin films of YBa 2 Cu 3 O 7 and found evidence for dipole transitions in vortex cores [6]. In addition, magneto-optical activity of the superconducting state was observed in these experiments [7]. For frequencies above the vortex resonance this chiral response is consistent with the cyclotron resonance of the mixed state. According to Kohn's theorem [8], for an isotropic, homogeneous electron system in a uniform applied magnetic field H, the only excitation produced by a uniform electrodynamic field is the cyclotron resonance at the frequency ω c = eH/mc, where m is the bare band mass.Thus, for an ideal, pure superconductor, cyclotron resonance is expected. From these considerations, one of the requirements of a theory of vortex dynamics is that it be consistent with Kohn's theorem. Commonly employed theories [1,3,4] fail this test since they are non-chiral.The matrix elements and selection rules for the dipole transitions in vortex cores have been studied by Jankó and Shore [9] and Zhu, Zhang and Drew [10]. Kopnin [11] proposed a peak in the electromagnetic absorption of pure superconductors due to these transitions. However Hsu [12,13] showed that these intravortex transitions are not excited by long wavelength probes in the clean limit. Instead the collective cyclotron motion of the center of mass i...