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Longitudinal and transversal permanent electric fields generated by an ac current through superconducting Pb and Nb thin strips have been studied as the function of the drive frequency (103≤f≤108 Hz), temperature, and magnetic field. At low frequencies (f<104 Hz) and below the critical temperature, the superconducting strips behave as one-dimensional rectifiers, whereas for higher drive frequencies (f>105 Hz) the rectification becomes two dimensional. The rectification strongly depends on the magnetic field, temperature and ac drive. The unusual dc electric field topology generated by the ac current in the superconducting strips can be explained by a local rectification due the oppositely directed asymmetric edge (Bean-Livingston type) barriers [ABSTRACT FROM AUTHOR]

We have studied electromagnetic flux guidance and confinement effects in NiFe cores, interconnecting three Al rings, to form a mesoscopic transformer-like device. Applying ac signals (of low amplitude and kHz frequency) to the contact pads of a semiclosed ring induced time-varying magnetic fields, which could be transferred to a nearby, closed ring, via the aid of a NiFe core. Similarly, a second core carried the fields of this ring, resulting from the induced signals, over to a third, semiclosed ring where readouts were performed over an applied load, using a lock-in amplifier. Highly linear curves of output versus input signal at stable phase were obtained with effective mutual inductance in the μH regime, giving an improvement of the order of 106 on the free field. [ABSTRACT FROM AUTHOR]