Article: published in Physical Review Applied by Antonio Lara member of Department of Condensed Matter Physics and Farkhad G. Aliev, IFIMAC researcher and member of the Department of Condensed Matter Physics.
Microwave stimulated superconductivity is apparently a counter intuitive phenomenon, its significance being dependent on vortex mobility and proximity to the critical temperature. Until now it was not clear whether this effect influences the penetration of magnetic flux via abrupt avalanches that is harmful for superconducting devices. This study shows that the triggered vortex avalanches in Pb superconducting films become efficiently inhibited close to the critical temperature or critical magnetic field. That happens when the frequency of the microwave stimulus is close to the vortex depinning frequency. These results pave the way to controlling avalanches in superconductor-based devices through their nonlinear response. [Full article]
Figure: a) Sketch of the sample. The golden stripline produces a magnetic field, represented by the red curling arrows, and with a calculated in plane amplitude given by the graph. Supposed distribution of magnetic flux – avalanches near the stripline and vortices far from it – is depicted in blue. b) Measured losses in the superconductor under a microwave excitation at f=7.55 GHz (color scale) as a function of temperature and microwave power. The gray scale dotted lines represent the triggering frequencies of different avalanche branches. The red dashed line is a guide for the eye that tracks the position of the minimum in microwave power required to trigger an avalanche.