Transport of magnetic vortices by surface acoustic waves

Abstract

In a thin film of superconducting YBCO the impact of surface acoustic waves (SAWs) traveling on the piezoelectric substrate is investigated. A pronounced interaction between the ultrasonic waves and the vortex system in the type II superconductor is observed. The occurrence of a SAW-induced dc voltage perpendicular to the sound path is interpreted as {\em dynamic pinning} of vortices by the piezoacoustic SAW, which acts as a conveyor for the fluxquanta. Its antisymmetry with respect to the magnetic field directly evidences the induced, directed flux motion.This dynamic manipulation of vortices can be seen as an important step towards flux-based electronic devices.Comment: submitte

Surface-acoustic-wave-induced AC–DC conversion in high- superconducting films

“…For this orientation Gutliansky predicted a peak in close vicinity to the superconducting transition as a signature for SAW-driven directed vortex motion. Gutliansky shows that the sign of this component changes sign with inverted applied magnetic field-as is expected if it is induced by forced directed vortex-motion [6].…”

“…However, if this peak was directly related to vortex-drag by the applied surface acoustic wave, it should reverse it's sign with sign-reversal of the applied static magnetic field-whatever the exact coupling between SAW and vortex-ensemble. A major component of the peak, however, does not (this was shown in [6]). Furthermore, the peak shows a non-intuitive field-dependence (see [6]) and is also observable at zero applied magnetic field.…”

“…A major component of the peak, however, does not (this was shown in [6]). Furthermore, the peak shows a non-intuitive field-dependence (see [6]) and is also observable at zero applied magnetic field. As is suggested by the presence of a DC component also by applying an AC driving current directly to the superconducting film, the observed voltage drop has to be of different origin.…”

“…Often the resulting DC voltage perpendicular to the path of expected vortexmovement is seen as proof for unidirectional vortex-transport. Surface-acoustic-wave-induced directed motion of magnetic vortices in superconductors was recently proposed [6] and the SAW-related induced DC-voltage was shown to consist of two parts, with only one being due to directed vortex motion. The origin of the additional DC-component is discussed here.…”

Transverse acousto-electric effect in superconductors

“…The standard time-dependent Ginzburg-Landau theory (TDGL), which contains the assumption of local equilibrium, and is formulated in the laboratory frame, is a powerful tool to study phenomena in the vicinity of the superconducting-normal phase transition. To study gyroscopes [1], gravitational wave antennae [2] and the interaction of the superconducting condensate with strong sound waves [3,4,5,6,7,8,9,10,11,12,13], where the atomic lattice is in motion, an extension to TDGL is needed to accommodate the dynamical system.…”