Growth of nano-composites and nano-alloys of Cu-Nb thin films

Parab, Pradnya; Bhui, Prabhjyot; Bose, Sangita

doi:10.1016/j.tsf.2016.12.040

Cited by 6 publications

(3 citation statements)

References 21 publications

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“…The substrate temperature was kept at 600 °C. In these films, the composition of Nb and Cu was varied by changing the ratio of the power densities (sputtering power/area of the target) of the two and they were grown for 5 min which resulted in films of thickness 145-250 nm [22]. These thicknesses are much larger than the superconducting coherence length (ξ∼11-17 nm) estimated from the critical field measurements (see section 3.2).…”

Section: Sample Preparation and Characterizationmentioning

confidence: 99%

Superconductivity in immiscible Nb–Cu nanocomposite films

Parab

Bagwe

Chalke

et al. 2017

Supercond. Sci. Technol.

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Superconductivity in granular films is controlled by the grain size and the intergrain coupling. In a two-component granular system formed by a random mixture of a normal metal (N) and a superconductor (S), the superconducting nano-grains may become coupled through S-N weak links, thereby affecting the superconducting properties of the network. We report on the study of superconductivity in immiscible Nb-Cu nanocomposite films with varying compositions. The microstructure of the films revealed the presence of phase separated, closely spaced, nano-grains of Nb and Cu whose sizes changed marginally with composition. The superconducting transition temperature (Tc0) of the films decreased with increasing concentration of Cu with a concomitant decrease in the upper critical field (Hc2) and the critical current (Ic). Our results indicate the presence of superconducting phasefluctuations in all films with varying Nb:Cu content which not only affected the temperature for the formation of a true phase coherent superconducting condensate in the films but also other superconducting properties.

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Section: Sample Preparation and Characterizationmentioning

confidence: 99%

Superconductivity in immiscible Nb–Cu nanocomposite films

Parab

Bagwe

Chalke

et al. 2017

Supercond. Sci. Technol.

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“…The grain size of the Nb and Cu crystallites varied with film composition and thickness, between 16 and 8 nm and 10 to 20 nm, respectively. More details of the growth and characterization of similar but thicker films can be found elsewhere 30 , 31 . For this work, films of varying thickness were grown with two different compositions of Nb:Cu.…”

Section: Methodsmentioning

confidence: 99%

Superfluid density from magnetic penetration depth measurements in Nb–Cu 3D nano-composite films

Gupta

Parab

Bose

2020

Sci Rep

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Superconductivity in 3D Nb–Cu nanocomposite granular films have been studied with varying thickness for two different compositions, Nb rich with 88 at% of Nb and Cu rich with 46 at% of Nb. For both compositions, the superconducting transition temperature (Tc) decreases with decreasing film thickness. For any thickness, doubling the Cu content in the films decreases the Tc by about 2 K. To explore if phase fluctuations play any role in superconductivity in these 3D films, the superfluid stiffness (JS) of the films was measured using low frequency two-coil mutual inductance (M) technique. Interestingly, the measurement of M in magnetic fields showed two peaks in the imaginary component of M for both Nb rich and Cu rich films. The two peaks were associated with the pair-breaking effect of the magnetic field on the intra and inter-granular coupling in these films consisting of random network of superconductor (S) and normal metal (N) nano-particles. Furthermore, JS was seen to decrease with decreasing film thickness and increasing Cu content. However, for all films studied JS remained higher than the superconducting energy gap (∆) indicating that phase fluctuations do not play any role in superconductivity in the film thickness and composition range investigated. Our results indicate that an interplay of quantum size effects (QSE) and superconducting proximity effect (SPE) controls the Tc with composition in these 3D nano-composite films.

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“…In the Nb-Cu films studied (which formed a random network of JJ arrays confirmed through transport measurements [121]), there were multiple evidence of the presence of PFs. Initially, 3D nanocomposite films with thicknesses between 160 and 250 nm were grown with varying composition of Nb:Cu by DC magnetron co-sputtering [118]. All the films grown at a substrate temperature of 600 • C were granular with phase separated Nb and Cu grains (see AFM image of one of the representative films in figure 8(a)).…”

Section: Role Of Pfsmentioning

confidence: 99%

A review of superconductivity in nanostructures—from nanogranular films to anti-dot arrays

Bose¹

2023

Supercond. Sci. Technol.

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Superconductivity in small particles has been studied since the early sixties. A large number of sample geometries for both one component elemental superconductors and dual component nano-composites having elemental superconducting particles dispersed in non-superconductng matrix have been explored which has helped us to understand the mechanism of the evolution of the superconducting transition temperature (Tc) with decreasing particle size. In this article, we review the work done in nano-structured superconductors from nano-granular films to these dual component superconducting nano-composites. In addition, we also present the experimental work done in superconducting films with periodic array of nano-sized holes showing the interesting property of vortex matching effect (VME) and try to understand the dominant mechanism for this phenomena.

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Growth of nano-composites and nano-alloys of Cu-Nb thin films

Cited by 6 publications

References 21 publications

Superconductivity in immiscible Nb–Cu nanocomposite films

Superconductivity in immiscible Nb–Cu nanocomposite films

Superfluid density from magnetic penetration depth measurements in Nb–Cu 3D nano-composite films

A review of superconductivity in nanostructures—from nanogranular films to anti-dot arrays

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