Strongly Enhanced Growth of High-Temperature Superconducting Films on an Advanced Metallic Template

Abstract

We demonstrate a straightforward and easily applied technique for growing BaZrO 3 doped YBa 2 Cu 3 O 6+x films of highly improved quality on a commercially used buffered metallic template by pulsed laser deposition. Our method relies on reducing the grain size of the target material, which completely prevents the transfer of the harmful grain boundaries or weak links from the substrate through the buffer layers on the deposited film. We have also observed a great improvement in the self-assembly of BaZrO 3 dopants, and the critical current density is increased in the high temperature range up to 40%. As an extra benefit, our method allows us to increasing the growth rate of the film by 25%. We have discussed the results comprehensively and provided quantitative insight into the underlying mechanisms. The presented technique can be considered a groundbreaking advancement for the vastly growing coated conductor industry.

Improved Crystalline Quality and Self-Field $J_{\mathrm{c}}$ in Sequentially Vacuum-Multilayered YBCO Thin Films on Buffered Metallic Templates

“…The asymmetry of the J c (θ) curve, especially in the vicinity of YBCO c-axis, can be explained by the film growth on the inclined buffer layer structure formed during the IBAD process, forming grain boundaries tilted from the normal vector of the surface [43], [44]. The formation of the c-axis peak is earlier connected to our nanograined target material, which in addition to reduced grain boundary transfer [7] decreases the twin domain size, leading to greater number of twin boundaries and other threading dislocations along the YBCO c-axis [39], [45]. In summary, we can conclude that the self-field properties are unquestionably improved by vacuummultilayering, which originate from the modified coherence length and penetration depth, and lengthening the electron mean free path of YBCO.…”

“…The YBCO multilayers of various layer thicknesses were manufactured by pulsed laser deposition (PLD) from the nanocrystalline YBCO target [7], [39] on metallic template (Hastelloy C276) with an advanced Al 2 O 3 /Y 2 O 3 /IBAD-MgO/LaMnO 3 /CeO 2 buffer layer structure (Fig. 1).…”

“…pulses producing 4×95 nm and 8×47 nm layer thicknesses were deposited applying 2 min vacuum treatment of 10 −3 torr between the layers. The details of the PLD system and buffer layer structures are given elsewhere [7], [40]. The crystalline quality was studied by x-ray diffractometry (XRD) with PANalytical Empyrean diffractometer in Bragg-Brentano mode.…”

“…T O maximize the absolute critical current density J c of YBCO thin films and coated conductors at high magnetic fields favourable for electric power applications [1]- [7], requirements of both the high crystalline quality and optimal flux pinning properties should be fulfilled [8]- [10]. The flux pinning structure organized with an artificially produced nanocolumn network within the YBCO matrix that maximally pins the vortices is widely studied [11]- [17], but the formation of crystalline defects that directly affect the shortening of the electron mean free path and thus the zero-field critical current density has got less attention in the field of hightemperature superconductors [9], [18]- [21].…”

Defining optimal thickness for maximal self-field Jc in YBCO/CeO2 multilayers grown on buffered metal

“…The YBCO multilayer structures, where various individual YBCO layer thicknesses (1L = 1 × 350 nm, 2L = 2 × 175 nm, 4L = 4 × 88 nm, 6L = 6 × 58 nm, 8L = 8 × 44 nm) together with alternating ≈23 nm thick CeO 2 layers, were grown by pulsed laser deposition on buffered metallic substrates (Hastelloy C276 with an advanced Al 2 O 3 /Y 2 O 3 /IBAD-MgO/LaMnO 3 /CeO 2 buffer layer) [39], as schematically illustrated in figure 1. The thickness and growth temperature of the CeO 2 layer, which grows with a 45 • in-plane tilt compared to the YBCO a/b-axes, were determined based on our previous optimizations and relevant literature.…”