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The recent development of nanofocused X-ray beams has paved the way to use them to directly pattern electronic devices at the nanoscale without the use of any photoresist, which is also known as the X-ray nanopatterning (XNP) technique. This novel patterning method is expected to become even more important with the advent of the 4th generation synchrotrons.
Here we report on an X-ray nano-patterning and nano-diffraction experiment performed on the high-temperature superconducting oxide Bi_2Sr_2CaCu_2O_8+δ (Bi-2212) aiming at clarifying the correlation between the changes in crystal structure and in electrical properties. The experiment has been carried out at the beamline ID13 at ESRF, where an X-ray beam 250×250 nm^2 in size at 14.85 keV was available. The Bi-2212 single crystals were mounted on electrical chips and have been monitored upon successive irradiation sessions up to a cumulative dose of about 1.9 x 10^11 Gy. Nano-XRD mapping has been performed between the irradiation sessions, allowing to resolve the spatial localization of the different crystal domains. Depending on the initial conditions of the crystals, our localized irradiations have induced some stress leading to a physical bending of the crystal, or, in case the crystal was already bent, have induced some stress release by creating a very small region with a low degree of crystallinity. Concerning the electrical properties, both the superconducting critical temperature and the normal state resistivity have been determined by means of a simple in-series resistor model. This has allowed us to observe for the first time an exponential dependence of the Bi-2212 resistivity on the irradiation dose, which gives access to highly underdoped superconducting regimes for this material, which cannot be obtained in any other way.
We think that these results represent an important step towards the development and the reliability of the XNP technique.
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