Introduction of c-axis-correlated 1D pinning centers and vortex Bose glass in Ba–Nb–O-doped ErBa₂Cu₃O_y films

Abstract

We report the effectiveness of barium niobate as a needle-type vortex pinning center, as well as a change in the vortex state in Ba–Nb–O (BNO)-doped ErBa2Cu3Oy thin films. BNO doping was effective for improving critical current properties for a magnetic field direction parallel to the c axis of a matrix film and induced the generation of columnar defects with diameters of 5–25 nm. The irreversibility lines were also changed by the BNO doping and were similar to those of heavy-ion-irradiated YBa2Cu3Oy crystals in which the vortex Bose glass state was induced. It is suggested that the characteristic field relevant to crossover from the Bose glass to collective pinned glass depends on the BNO doping level. There is a possibility that Ba-based perovskite-type oxides promote the formation of nanorods universally and these nanorods play the role of one-dimensional c-axis-correlated pinning centers.

Influence of Growth Temperature on Microstructure and Superconducting Properties of ${\rm ErBa}_{2}{\rm Cu}_{3}{\rm O}_{7-\delta}$ Films With ${\rm Ba}({\rm Er}_{0.5}{\rm Nb}_{0.5}){\rm O}_{3}$ Nanorods

“…The BENO nanorods could provide effective -axis correlated pining centers at a lower growth temperature [6], [8]. The seems to relate closely with nanorod growth.…”

“…The seems to relate closely with nanorod growth. Another recent report, it was demonstrated that BENO nanorods were thinner in diameter and distributed at higher density at a lower [6], [9]. However, the nanorods became curved with a deviation from the -axis direction of the film at a lower .…”

“…Recently, improvement of performance in external magnetic fields at 77 K has been demonstrated by introducing artificial pinning centers (APCs) in the REBCO films [1]- [6]. Driscoll et al [1] have reported large enhancement in a magnetic field on parallel to the -axis using (YBCO) films with (BZO) doping.…”

Enhancing critical current in YBCO thick films: Substrate decoration and quasi-superlattice approach

“…BaZrO 3 has been used most commonly as a target impurity addition [4], and has been shown [18] to be able to self-organize into correlated nano-rods within the film microstructure. More recently, BaNb 2 O 6 and BaSnO 3 [19,20] and BaSnO 3 has been added to YBCO [21]. Another secondary phase addition to the target that proved to create strong pinning centres is Gd 2 Ba 4 Cu-WO 12 [22].…”

Characterization of nanorods in BaNb2O6-doped Er123 films revealed by cross-sectional transmission electron microscopy

“…On the other hand, BaNb 2 O 6 (BNO)-doped Er123 bulk material was [13]. We reported the transport properties of a BNO-doped Er123 film [14].…”