Local magnetic field detector made by microscale ion irradiation on high temperature superconducting films

Abstract

Microscale modulations of the crystal structure in a continuous superconductor turn out to be effective for the spatial focusing of the energy dissipation induced by unpinned vortices. High-energy heavy-ion irradiation allowed the authors to finely control the defect density in order to study the properties of interfaces between pristine and irradiated parts of high temperature superconductors. In particular, strip-shaped samples were locally irradiated to create microscale modulations across their whole width. Magneto-optical imaging under electrical transport and magnetoresistive measurements imply that such tailored modulation in a superconducting strip can be exploited to develop a fully planar, single-compound, local magnetoresistive sensor.

THz Detection Above 77 K in YBCO Films Patterned by Heavy-Ion Lithography

“…As summarized in the introduction, the HEHI irradiation induces structural modifications both in the substrate and in the HTSC film. The strain due to ion implantation in the substrate causes a local increase of the YBCO film thickness, experimentally determined by Atomic Force Microscopy [11], [13]. Columnar defects are induced in the HTSC film and generate in-plane stress and amorphization of the material on the nanometric scale.…”

“…This approach leads to the functional decoupling of such modulated micro-regions with respect to the as-grown ones in the YBCO films, because in dependence on the temperature and the bias current of patterned samples, it is possible to localize the dissipation due to external electromagnetic signals. Recently, YBCO strip-shaped films patterned by HEHI were indeed exploited for developing low-power magnetic field detectors [11]. In that case, the voltage detected across the strip, as induced by an external magnetic field, is only due to the electrical power dissipation occurring in the irradiated region [12], [13].…”

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

“…At these fluences the critical temperature T C is also reduced in the channel region, mainly due to secondary electrons affecting the regions around the amorphous columns and to irradiation induced strain in the substrate 24 . Furthermore, the presence of the amorphous columnar defects reduces the volume of the film that actually supports superconductivity, resulting in local suppression of the carrier density in the channel which influences the NLME.…”

“…By means of a stainless steel micro-collimator, a 55 m wide channel was created with a uniform distribution of ion-induced defects, which are mainly columns of amorphized material with nanometric cross-section forming along the ion track. The channel material shows a slight topographic elevation from the rest of the film 24 due to strain induced by implantation of the ions into the substrate to a depth of about 13 m below the film surface. Moreover, the columnar defects impose non-superconducting regions in the film, thus suppressing the carrier density in the channel.…”

Nanostructured microsize YBCO mesas for applications as field sensors

“…The main issue addressed in this paper concerns structural modifications of the interface region between virgin and modified zones [8][9][10][11], leading to mesa-like distribution of nanostructured regions. The function of such mesas as magnetoresistive sensor units is then shown and discussed.…”