Microwave nonlinearity and photoresponse of superconducting resonators with columnar defect micro-channels

Abstract

Micro-channels of nanosized columnar tracks were planted by heavy-ion irradiation into superconducting microwave microstrip resonators that were patterned from YBa 2 Cu 3 O 7-x thin films on LaAlO 3 substrates. Three different ion fluences were used, producing different column densities, with each fluence having a successively greater impact on the microwave nonlinearity of the device, as compared to a control sample. Photoresponse images made with a 638 nm rastered laser beam revealed that the channel is a location of enhanced photoresponse and a hot spot for the generation of intermodulation distortion. The microwave photoresponse technique was also advanced in this work by investigating the role of coupling strength on the distribution of photoresponse between inductive and resistive components.

Relaxation of Microwave Nonlinearity in a Cuprate Superconducting Resonator

“…Raster scanning the probe across the patterned superconductor can produce spatial mapping of the even and the odd order IMD [16]. A spatial map of the 3rd orders IMD in a region of the resonator with 200 µm wide lines is shown in Fig.…”

Local Whole-Device Scanning of Distortion in Superconducting Microwave Resonators

“…Ref. [17] investigated hot spots in third order IMD due to a defect engineered by heavy ion beam irradiation. Both Refs.…”

“…Opportunities are opened up by this capability, which are illustrated by these and other recent results. Those explored thus far include searching for nonlinearity hot spots [17], understanding the distinction between second and third order nonlinearity [ 20 ], and modelling the contribution of fluxons to nonlinearity [12].…”

“…Both Refs. [17] and [21] used photoresponse to generate highly resolved third order IMD images. The currently reported technique enables synchronous comparison of the two orders.…”

“…In Ref. [17], the probe moved along a section of a hair-pin resonator producing a 1-dimensional map of the IMD that corresponded primarily to current in the structure. An IMD hot-spot at an engineered defect was clearly visible.…”