Structural and functional modifications induced by X-ray nanopatterning in Bi-2212 single crystals

Abstract

We have investigated the modifications induced in the high-Tc superconductor Bi2Sr2CaCu2O8+δ (Bi-2212) by X-ray nanopatterning, which is an innovative, photoresist-free, direct-writing approach recently used to fabricate proof-of-concept electrical devices [Truccato et al., Nano Lett. 2016, 16, 1669. By means of combined synchrotron microdiffraction and electrical transport measurements carried out on the same Bi-2212 microcrystal, we show that hard X-ray irradiation with fluences of the order of 10 12 J/m 2 , corresponding to doses of the order of 10 13 Gy, induces crystal fragmentation into multiple subdomains and decreases the carrier density of the system. We ascertain that the synergistic action of grain boundaries and of oxygen removal from the material dramatically changes the properties of Bi-2212 both in the normal and in the superconducting state. This special feature of X-ray nanopatterning introduces an opportunity that could be exploited to finely tune material structural defects according to the desired properties.

Mapping of Structural Changes Induced by X-ray Nanopatterning via Nano-X-ray Diffraction and Corresponding Electrical Effects

“…Each d -spacing was obtained evaluating the centroid position on the curves resulting from the radial integration of a maximum projection of a 10–20° φ scan with a fine step. The value obtained for the crystal in this pristine condition is c = 30.536(5) Å, which corresponds to a heavily OD regime. , …”

“…A rocking curve of reflection (006 1) was measured with an angular resolution of 0.01°at this position revealing a FWHM ≅ 0.06°, which indicates a very good crystallinity of this sample that is comparable to the free-standing Bi-2212 crystals analyzed by our group in a previous experiment. 29 In order to complete the characterization of the region prior to damaging, a y,z-scanning was acquired around the position D1 at the ϕ value coinciding with the maximum of the rocking curve. Figure 4a shows the maximum intensity projection of this measurement for the same portion of the detector as in Figure 3a.…”

“…The presence of two separated subpeaks is clearly visible, with an angular distance between their centroids equal to 1.37°, as calculated from the beam center. This increase in the spread of the crystal mosaicity by about 1° is comparable to what was already observed by our group in a previous paper, even if in that case the CF and CD values were at least 20-fold larger . However, this observation testifies to the appearance of two misaligned crystal domains connected by a [010]-tilted grain boundary.…”

Time and space resolved modelling of the heating induced by synchrotron X-ray nanobeams

“…In this background, we have recently demonstrated the feasibility of a new patterning concept, based on a resist-free method, which exploits the structural and electrical modifications induced in condensed matter by high-intensity nanometric beams from third-generation synchrotrons (Bonino et al, 2019;Pagliero et al, 2014;Truccato et al, 2016;Mino et al, 2017Mino et al, , 2019. For example, by irradiating the high-temperature superconductors Bi 2 Sr 2 CaCu 2 O 8+ and YBa 2 Ca 3 O 7À with a 17 keV nanobeam with a flux of $10 11 photons s À1 , a change in the electrical behaviour was related to an increase in the crystal mosaicity and a depletion of the doping oxygen content (Bonino et al, 2018(Bonino et al, , 2019. Following these findings, we exploited these local modifications to nanopattern three Bi 2 Sr 2 CaCu 2 O 8+ microcrystals, finally fabricating electrical devices based on the Josephson effect (Pagliero et al, 2014;Truccato et al, 2016;Mino et al, 2017).…”

Functional Modifications Induced via X‐ray Nanopatterning in TiO2 Rutile Single Crystals

“…Indeed, some of us have already shown that, using synchrotron radiation nanoprobes with sizes of the order of 50 Â 50 nm 2 and modifying the corresponding photon flux and dose, it is possible to switch from ordinary material characterization to material modification. [21][22][23][24][25][26][27] In the case that a superconducting oxide is irradiated in an approximately uniform way, this treatment corresponds to a variation of its oxygen doping level, [28][29][30] but if only some carefully designed portions are irradiated, a current path can be drawn in the material in such a way to fabricate a Josephson device. [31] Thus, the whole technique can be considered an alternative X-ray nanopatterning (XNP) method to locally introduce defects in oxides and fabricate devices as desired without etching the crystals.…”