YBa2Cu3O7-delta Research Articles

Структура, морфология, транспорт и механизм потери кислорода в тонких пленках YBa-=SUB=-2-=/SUB=-Cu-=SUB=-3-=/SUB=-O-=SUB=-7-delta-=/SUB=-, полученных импульсным лазерным напылением со скоростной фильтрацией эрозионного факела

We report the study of YBa2Cu3O7‒delta films, synthesized on SrTiO3(100) substrates by pulsed laser deposition with velocity filtration, using X-ray diffractometry, transport measurements, and scanning electron microscopy. We have revealed the dependence of the structure of 100-200 nm thick YBa2Cu3O7‒delta films on deposition time and velocity of particles in erosion plume, set by velocity filter. After deposition, the films, or their part, close to the substrate, consisted of 3‒10-nm crystals with oxygen index delta = 0.08, the same as in the target. For deposition time from 10 to 60 min, we observed the growth of regular pyramids with triangular and quadrangular bases from 20 to 500 nm in size at the base and spiral pyramids with polygonal bases on the film surface. The maximum oxygen loss up to delta = 0.35 and T (R = 0) up to 77.4 K coincided with the appearance of spiral pyramids up to 100 nm-high. These findings evidence in favor of oxygen depletion of the top layers of YBa2Cu3O7‒delta thin films through the formation and growth of oxygen-deficient pyramids on their surface. The oxygen index in the range of delta = 0.08‒0.15 in both nanocrystals and regular pyramids of 20‒300 nm in size provided T(R = 0) =84‒87 K and the width of superconducting transition DeltaT = 2.5‒3.5 K.

Unravelling the Crystallization Process in Solution-Derived YBa2Cu3O7-δ Nanocomposite Films with Preformed ZrO2 Nanocrystals via Definitive Screening Design.

A low-cost chemical solution deposition technique was employed to prepare YBa2Cu3O7-δ (YBCO) nanocomposite films starting from a colloidal solution containing preformed ZrO2 nanocrystals. As previous publications revealed, an increase in the amount of nanocrystals results in a progressive deterioration of the film properties. The parameters that control this process and their interplay are still unknown in detail. Using definitive screening design (DSD), a design-of-experiments approach, allowed determining which of the multiple growth parameters play a key role for improving the superconducting properties of YBCO nanocomposite films even with a large concentration of nanocrystals. In order to show the potential of DSD, it has been applied for the optimization of two different properties: the critical temperature Tc and the full width at half-maximum of the (005) YBCO reflection. This work shows that DSD is a powerful and efficient method that allows optimizing certain processes with a minimal number of experiments.

Fabricating Nanogaps inYBa2Cu3O7−δfor Hybrid Proximity-Based Josephson Junctions

The advances of nanotechnologies applied to high-critical-temperature superconductors (HTSs) have recently given a huge boost to the field, opening new prospectives for their integration in hybrid devices. The feasibility of this research goes through the realization of HTS nanogaps with superconductive properties close to the as-grown bulk material at the nanoscale. Here we present a fabrication approach allowing the realization of YBa2Cu3O7-delta (YBCO) nanogaps with dimensions as small as 35 nm. To assess the quality of the nanogaps, we measure, before and after an ozone treatment, the current-voltage characteristics and the resistance versus temperature of YBCO nanowires with various widths and lengths, fabricated by using different lithographic processes. The analysis of the superconducting transition with a thermally activated vortex-entry model allows us to determine the maximum damage the nanowires undergo during the patterning which relates to the upper bound for the dimension of the nanogap. We find that the effective width of the nanogap is of the order of 100 nm at the superconducting transition temperature while retaining the geometrical value of about 35 nm at lower temperatures. The feasibility of the nanogaps for hybrid Josephson devices is demonstrated by bridging them with thin Au films. We detect a Josephson coupling up to 85 K with an almost ideal magnetic-field response of the Josephson current. These results pave the way for the realization of complex hybrid devices, where tiny HTS nanogaps can be instrumental to study the Josephson effect through barriers such as topological insulators or graphene.

Study of Structure and Properties of Cadmium-oxide-doped YBa2Cu3O7–delta Superconductor Using XRD Patterns: A Numerical Investigation

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Long-range proximity effect in La2/3Ca1/3MnO3/(100)YBa2Cu3O7−δferromagnet/superconductor bilayers: Evidence for induced triplet superconductivity in the ferromagnet

Scanning tunneling spectroscopy measurements conducted on epitaxially grown bilayers of half-metallic ferromagnetic La2/3Ca1/3MnO3 (LCMO) on superconducting (SC) (100)YBa2Cu3O7-delta (YBCO) reveal long-range penetration of superconducting order into the LCMO. This anomalous proximity effect manifests itself in the tunneling spectra measured on the LCMO layer as gaps and zero bias conductance peaks. Remarkably, these proximity-induced spectral features were observed for bilayers with LCMO thickness of up to 30 nm, an order of magnitude larger than the expected ferromagnetic coherence length in LCMO. We argue that this long-range proximity effect can be accounted for by the formation of spin triplet pairing at the LCMO side of the bilayer due to magnetic inhomogeneity at the interface or at domain walls. Possible symmetries of the induced order parameter are discussed.

Cerium Oxide Buffer Layers on Perovskite-Type Substrates for Preparation of $c$-Axis-Oriented ${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7}$ Films by Fluorine-Free Metalorganic Deposition

c-axis-oriented epitaxial YBa2Cu3O7-delta (YBCO) superconducting films were prepared on perovskite-type single crystal substrates, i.e., SrTiO3, LaAlO3, NdGaO3 and YAlO3 with cerium oxide (CeO2) buffer layers by fluorine-free metalorganic deposition (MOD) at relatively low heating rates. The YBCO films on these CeO2-buffered substrates exhibited high critical current densities with an average of 3-5 MA/cm2 at 77.3 K. Using CeO2 buffer layers we could avoid the occurrence of undesired a-axis-oriented grains of YBCO on these substrates despite employing lower heating rates. The lattice constants of YBCO films, CeO2 buffer and substrates were compared. It was found that both the YBCO films and CeO2 buffer were elastically deformed.

Intermodulation Distortion in Epitaxial Y-Ba-Cu-O Thick Films and Multilayers

We report intermodulation distortion (IMD) in high-quality epitaxial YBa2Cu3O7-delta (YBCO) thick films and multilayers prepared by pulsed-laser deposition (PLD) using multiple targets. Two sets of films were prepared: single-layer and multilayer YBCO films in which a 20-nm-thick CeO2 inter layer is inserted between every 100-nm-thick YBCO layer. With increasing YBCO thickness from 200 nm to 1200 nm, single-layer films exhibited improvement of IMD, whereas multilayer films showed degradation of IMD. Similarly, YBCO crystalline quality in single-layer films was improved with increasing the thickness, while that in multi-layers films degraded. These results suggest that there is a strong correlation between crystalline quality and IMD for YBCO films. The comparison of experimental data with the theory of IMD suggests that improving crystalline quality is essential for YBCO films with thickness greater than 1 mum to achieve an intrinsic nonlinear behavior. PLD using multiple targets is a very useful method to grow thick YBCO films with high crystalline quality and low IMD.

Electrodeposited Biaxially Textured Buffer Layers for YBCO Superconductors

Non-vacuum electrodeposition (ED) was used to prepare simplified Gd2O3/Gd2Zr2O7 and CeO2/Gd2Zr2O7 buffer layers on a Ni-W substrate. Post-annealing conditions of electrodeposited precursor films were optimized to obtain high-quality biaxially textured buffer layers. The buffer layers were characterized by X-ray diffraction, optical profiling, and transmission electron microscopy (TEM). The effect of the cap layer thickness on the surface morphology and texture of the buffers was also studied. The microstructure of CeO2/Gd2Zr2O7 was analysed and compared to Gd2O3/Gd2Zr2O7. The high-resolution TEM shows biaxially textured crystalline elctrodeposited Gd2O3 and CeO2 cap layers on the electrodeposited Gd2Zr2O7 layers without any defects. YBa2Cu3O7-delta (YBCO) superconductor was deposited by pulsed laser deposition (PLD) on the simplified ED-Gd2O3/Gd2Zr2O7 and ED-CeO2/Gd2Zr2O7 buffers. Transport current density of 3.3 MA/cm2 at 77 K was obtained for PLD YBCO deposited on ED-Gd2O3/Gd2Zr2O7 buffer layers.

Practical Magnetic Pinning in YBCO

Iron-containing oxide inclusions have been incorporated as nanoscale ferromagnetic precipitate flux pinning centers within pulsed laser deposited YBa <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7-delta</sub> (YBCO) thin films via a simple process utilizing a composite deposition target. The resultant films exhibit a coexistence of superconductivity and ferromagnetism at 77 K, and a consequent significant enhancement in their absolute critical current density, J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> , compared to pure YBCO films prepared under the same conditions. dasiaPoisoningpsila effects due to the incorporation of Fe into the YBCO matrix are avoided at sufficiently low concentrations of inclusions, where the greatest self-field J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> enhancement is seen, but do become increasingly evident as the concentration is increased. The process outlined has practical application in the synthesis of high-J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> YBCO films, with the absolute J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> values obtained in initial samples lying at the upper bound of reported values for samples produced worldwide to date.

Vortex Trapping in Hybrid Magnetometers

Hybrid magnetometers based on a normal conducting sensor and a superconducting flux concentrator have been investigated. When this sensor is operated in an unshielded environment flux vortices can be trapped in the superconducting body when the sensor is cooled. Thermal hopping of the trapped vortices gives rise to 1/f noise. The mechanism for vortex trapping has been investigated. A new model for the critical field for vortex trapping and vortex densities has been derived. Experimental verification on YBa2Cu3O7-delta (YBCO) strips with a Scanning SQUID Microscope shows very good agreement between measurements and the new theory. The results have been applied in a hybrid magnetometer design based on a bismuth Hall sensor and an YBCO flux concentrator. Measurements show a field gain up to G=7 with a large effective range of 175uT.

Growth of Thick ${\rm BaZrO}_{3}$-Doped ${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7-\delta}$ Films With High Critical Currents in High Applied Magnetic Fields

High quality, thick YBa2Cu3O7-delta (YBCO) films with splayed, self-assembled BaZrO3 insulating nanodot columns were epitaxially grown by pulsed laser deposition on short pieces of ion-beam-assisted deposition (IBAD) MgO substrate. Variations in superconducting and microstructural properties were observed for samples grown at different substrate temperatures between 790 and 810degC. At substrate temperatures between 790 and 800degC, samples were measured to have large self-field I c of 670-787 A/cm at 77 K and minimum I c of 353-392 A/cm for all angles at 65 K, 3 T.

Interfacial Defects and Flux-Pinning Effects in Nanostructured ${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7-\delta}$ Thin Films

In this work, we conducted a detailed microstructural study on several selected nanostructured YBa <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7-delta</sub> (YBCO) thin films processed using sectioned targets. All samples were deposited by a pulsed laser deposition technique. The doping materials include CeO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , BaZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> , and Y <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> . The interfacial defects, including misfit dislocations and secondary phases in different systems were studied and compared using cross-section transmission electron microscopy (TEM) and high resolution TEM. We also conducted detailed superconducting property measurements to correlate these interfacial defects for different systems with their flux-pinning properties.

YBCO Films With ${\rm Zr}^{4+}$ Doping Grown by MOD Method

YBa <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7-delta</sub> (YBCO) films with Zr doping have been prepared successfully by the trifluoroacetate metal-organic deposition (TFA-MOD) method through dissolving Zr acetylacetonate into the precursor solution. Yttria-stabilized zirconia(YSZ)nanoparticles were detected in the doped YBCO films by XRD. From the analysis of XRD omega and phi scans, the doped films have better out-of-plane and in-plane textures than those of the un-doped YBCO film. Although the doped YBCO films have lower <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> than that of the un-doped YBCO film, a very significant enhancement of normalized <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">J</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> is displayed as compared to the undoped film at applied fields, indicating that an effective pinning force was created by Zr doping.

Detection of Magnetic Signal in High-Tc Superconductor Devices by Scanning Laser Magneto-Optical Microscope

We have fabricated a superconducting vortex flow transistor (SVFT) device with a YBa2Cu3O7-delta (YBCO) thin film on an MgO substrate. To detect the local magnetic flux state inside the superconducting loop of the device, we utilized a scanning laser magneto-optical microscope (SLMO). As a result we have succeeded in the observation of magnetic flux distribution in the device by applying dc-control current larger than 100 mA. Moreover, we could detect the time variation of local magnetic field in the superconducting loop as the MO signals by applying ac-control current with an amplitude of 100 mA at 500 Hz.

Long, Highly-Ordered High-Temperature Superconductor Nanowire Arrays

The preparation and electrical properties of high-temperature superconductor nanowire arrays are reported for the first time. YBa2Cu3O(7-delta) nanowires with widths as small as 10 nm (much smaller than the magnetic penetration depth) and lengths up to 200 microm are studied by four-point electrical measurements. All nanowires exhibit a superconducting transition above liquid nitrogen temperature and a transition temperature width that depends strongly upon the nanowire dimensions. Nanowire size effects are systematically studied, and the results are modeled satisfactorily using phase-slip theories that generate reasonable parameters. These nanowires can function as superconducting nanoelectronic components over much wider temperature ranges as compared to conventional superconductor nanowires.

Surface Morphology and Microstructure of Thick ${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7-\delta}$ Films on Vicinal $r$-Cut Sapphire Buffered With ${\rm CeO}_{2}$

Microcrack-free thick YBa2Cu3O7-delta (YBCO) films were successfully fabricated by pulsed laser deposition on deliberately miscut AI2O3 (1102) (5.22deg off towards [1102]) buffered with CeO2. Characterization of the films revealed a porous morphology, consisting of interconnected islands and deep holes (pores). The microstructure of the YBCO films was further investigated by cross-section (cut along both AI2O3 [1101] and [1120] transmission electron microscopy (TEM). No apparent interface reaction is seen for all the TEM observations. A high density of linear defects aligned near c-axis are frequently observed. All the defects are initiated from the YBCO / CeO2 interface, indicating the importance of the microstructure of the CeO2 buffer layer and the sapphire substrate for the growth of YBCO. In addition, numerous small stacking faults lying in the alpha - b-plane of YBCO were produced by the linear defects. The high density of the growth-induced defects may act as strong pinning centers in YBCO films and therefore increase Jc of the film.

${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7-\delta}$ Films With ${\rm BaZrO}_{3}$ Inclusions for Strong-Pinning in Superconducting Films on Single Crystal Substrate

The addition of artificially induced defects improves the pinning efficiency of magnetic flux vortices in YBa2Cu3O7-delta (YBCO) films. In YBCO films by pulsed laser ablation (PLD) technique this goal can be pursued by the introduction of epitaxial second phase nanoinclusions in the YBCO matrix. In the present work, the effect of BaZrO3 (BZO) inclusions in stoichiometric YBCO films on transport properties has been studied. Composite targets obtained by addition of BZO powder in molar percents ranging from 2.5 to 7 mol.% have been prepared with BZO mean grain size of about 1 mum. Structural and morphological characterizations of the films obtained by PLD from these targets have been carried out through X-ray diffractometry and Scanning Electron Microscopy (SEM) analysis. Dc electrical transport measurements at 77 K have revealed a better magnetic field retention of the critical current density, Jc, being at 3 T the 14.6% and the 16.4% of the zero field values for YBCO-BZO 5% and 7%, respectively. The complex surface impedance has been measured by means of a dielectric resonator at a high microwave frequency (50 GHz). In order to identify the potentially strong pinning induced by the inclusions, the field-dependent complex resistivity has been determined as a function of temperature in a moderate magnetic field (B < 1T). Very high depinning frequency are estimated in YBCO films with BZO inclusions indicating extremely high vortex pinning and steep potential wells.

Substrate Surface Decoration With ${\rm CeO}_{2}$ Nanoparticles: An Effective Method for Improving Flux Pinning in ${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7-\delta}$ Films

We have demonstrated improved critical current density, Jc, in YBa2Cu3O7-delta (YBCO) films through a controlled study of substrate surface modifications with nano-sized second-phase pre-formed CeO2 particles. Nanoparticles were applied to single crystal SrTiO3 surfaces using suspension-based techniques prior to YBCO film growth. With the introduction of CeO2 nanoparticles, YBCO films showed more robust field dependence at intermediate fields (Jc prop B-prop), where a smaller power law exponent of alpha ~ 0.3 is obtained. The self-flefd Jc(77K, Bparc) values of the YBCO films on reference and CeO2 modified substrates are 1.1 and 1.9 MA/cm2 ; and at 1 Tesla 0.1 and 0.52 MA/cm2 , respectively. Consistent with this alpha-value, angular field dependent Jc and transmission electron microscopy studies indicate the presence of c-axis aligned correlated defects in these modified samples.

Disorder Effects on the Intrinsic Nonlinear Current Density in ${\rm YBa}_{2}{\rm Cu}_{3}{\rm O}_{7-\delta}$

We present harmonic generation measurements of the intrinsic nonlinear current density j <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> of YBa <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7-delta</sub> (YBCO) films at temperatures close the T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> . Experiments on a range of different quality samples allow us to extract the dependence of j <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> on the penetration depth of the superconductor. In order to model these results, we calculate the intrinsic nonlinear current response of d <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-y</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> -wave superconductors in the Meissner regime in the presence of nonmagnetic impurities within the self-consistent T-matrix approximation.

Fabrication of High-$J_{\rm c}$${\rm NdBa}_{2}{\rm Cu}_{3}{\rm O}_{7-\delta}$ and ${\rm BaZrO}_{3}$-doped ${\rm NdBa}_{2}{\rm Cu}_{3}{\rm O}_{7-\delta}$ Films on RABiTS

Critical current densities (J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> ) over 2 MA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> have been obtained for epitaxial NdBa <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7-delta</sub> (NdBCO) films deposited via pulsed laser deposition on RABiTS having the configuration of Ni - 3at.%W /Y <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /YSZ/CeO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . Compared to YBa <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7-delta</sub> (YBCO) films on RABiTS, enhanced J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> in applied magnetic fields is observed for the NdBCO films. Further improvement in in-field J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> is achieved by incorporation of self-assembled BaZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (BZO) nanodots within the NdBCO film. At intermediate fields J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> varies as J <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</sub> ~ H <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-alpha</sup> , with alpha values for un-doped and BZO-doped films being ~0.43 and ~0.37 respectively, significantly lower than alpha ~ 0.52 for pure YBCO films. Combined effects of better pinning in NdBCO films over YBCO films as well as creation of columnar defects via incorporation of self-assembled BZO nanodots, result in significant improvement over pure YBCO films on RABiTS.