The AC Hall effect in YBCO: temperature and frequency dependence of Hall scattering

We measure the Hall angle, theta(H), in YBCO films in the far- and mid-infr ared to determine the temperature T and frequency omega dependence of the H all scattering. Using novel polarization modulation techniques we measure b oth the Faraday rotation and ellipticity induced by these films in high mag netic fields to deduce the complex conductivity tensor. We observe a strong temperature dependence of the Hall conductivity in sharp contrast to the w eak dependence of the longitudinal conductivity. By fitting the frequency-d ependent normal state Hall angle to a Lorentzian theta(H)(omega) = omega(H) /(gamma(H) = i omega) we find the Hall frequency, omega(H), is nearly indep endent of temperature. The Hall scattering rate, theta(H)(omega) is consist ent with gamma(H) approximate to T-2 and is remarkably independent of IR fr equency suggesting non-Fermi liquid behavior. (C) 2000 Published by Elsevie r Science B.V. All rights reserved.