Microwave Magneto-Surface Impedance of High- T _c Superconductors

Abstract

Magnetic-field-induced microwave absorption in sintered high-T, copper oxide superconductors is found to be proportional to the surface area of samples and not to their volume, establishing that absorption takes place near the sample surface. The surface resistance and reactance increase with magnetic field as a result of energy loss through fluxons driven by superconducting currents. When the magnetic field is modulated, absorptive and dispersive signals arise from modulation of the complex surface impedance through processes induced by the changing magnetic fields.

Magnetically modulated microwave absorption in cuprate superconductors

“…6. The linearity of these plots, and the temperature dependence of AP/AH has been discussed by Portis et al [23] and Marcon et al [24] in terms of a viscous flux flow model. Around 93 K the plots become sublinear possibly due to ah increased coupling between the vortices.…”

Single Particle Motion in One-Dimensional Pinning Potentials

“…A similar approximation considering the periodic impurity pinning centers in 1D has already been made by Inui et al [60]. Thus, the equation of motion of a vortex neglecting the effective mass [40,41,80] can be written in differential form as follows:…”

Apparatus for nonresonant rf power absorption studies in high Tc superconductors and CMR materials using rf oscillators

“…For sample #1 the power absorption smoothly and monotonically increases with increasing applied field and shows a tendency to saturate at higher fields. We ascribe this change to be directly associated with the Joshepson Junction decoupling [13] and fluxon motion [14] in high T c superconductors. The shape of the curves and the opposite behavior in these In our second experiment we investigated with manganite sample.…”