The intrinsic effects of a magnetic field on the microwave properties of sor d order parameter symmetry in high-T-c superconductors

A theoretical discussion of the intrinsic effects of a magnetic field on th e real and imaginary parts of the ac electrical characteristics of supercon ductors is reported. The subsequent phenomenological theory emphasizes only the role of the scattering mechanisms of quasi-particles by static indepen dent vortices. However both s- and d-wave order parameter symmetries are co nsidered. Power laws for the field dependence at low temperature are obtain ed: Delta R-s similar or equal to B/B-c2, Delta X-s similar or equal to (B/ B-c2)(2) and Delta R-d similar or equal to (B/B-c2)(3/2) Delta X-d similar or equal to B/B-c2 for an s and a d gap respectively, Delta X-s similar or equal to (Delta R-s)(2) and Delta X-d similar or equal to (Delta R-d)(2/3) while (sigma(1)/sigma(2))(s) similar or equal to B and (sigma(1)/sigma(2))( d) similar or equal to B-1/2. Since the published data do not seem to be (a lways) in agreement with these laws, this indicates effects of 'extrinsic o rigin', e.g. granularity and weak links. A mixed order parameter symmetry c annot be ruled out in cases where these extrinsic effects occur.