Magnetization jumps in a lead-porous glass composite: Experiment and simulation

An ac magnetization technique was used to study superconductivity in tin loaded nanoporous silica matrices, opal matrix and two porous glasses. The behavior of type-II superconductors with a sharp transition at zero bias field was observed. Regular increase in the superconducting temperature up to 4.2 K and in a critical field up to H c2 (0) ∼ = 54 kOe with decreasing pore size was found. A crossover from the upturn to the common downturn curvature in the H c2 (T) line was seen for all nanocomposites; the upturn curvature was more pronounced for the matrix with the finest pores.

Section: Introductionmentioning

confidence: 99%

Superconductivity in Sn nanocomposites

Ciou¹,

Lee²,

Charnaya³

et al. 2013

“…Studies on ordered In-opal nano-composites were also carried out where superconductivity was seen to be influenced when the size of the In was comparable to the superconducting coherence length [106]. Later, in such systems, an interesting interplay between the weak and strong Josephson coupled nanoparticles was observed from electrical and magnetic measurements [103,107,108]. At the same time, there were a few reports on the random network of superconducting-metal nano-composites in which percolation models were used to understand the transport properties [48,99].…”

Section: Variation Of Superconducting Transition Temperature (Tc)mentioning

confidence: 99%

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

Bose¹

2023

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.

“…Since the discovery of the flux-jump phenomenon in SCs, a great deal of efforts has been made to reveal its underlying instability mechanism [6][7][8][9][10][11][12][13][14]. It is generally known that under appropriate conditions, the critical state of a SC may become unstable if it undergoes a small fluctuation of either the external magnetic field or the temperature.…”

Section: Introductionmentioning

confidence: 99%

Thermomagnetic instability and accompanied stress intensity factor jumps in type-II superconducting bulks under various magnetization processes

Huang¹,

Song²,

Wang³

et al. 2022

For type-II superconducting bulks used as trapped-field magnets, the thermomagnetic instability, manifested as flux jumps and temperature spikes, frequently takes place, resulting in a large amount of energy dissipation in a short time and further the crack problem due to electromagnetic and thermal stresses. In this paper, based on the magnetic and heat diffusion equations and fracture theory, we develop a thermal-magnetic-mechanical coupling model to analyze the flux-jump and fracture behaviors in bulk samples of BiSrCaCuO under various magnetization processes. This model has an important advantage that the simulation domain can be restricted to the sample itself, without having to consider the air region around it, and its reliability is verified by the existing experimental and numerical results. The effects of the sample size, the ambient temperature, and the sweep rate, direction, and uniformity of the external magnetic field on the flux jumps, and Mode I and Mode II stress intensity factors are fully analyzed under different cooling conditions. It is found that as ambient temperature or field inclined angle increases or field sweep rate decreases, the first flux-jump field presents a trend of monotonically increasing for zero-field-cooling magnetization but it has an opposite trend for field-cooling magnetization. The flux jump can lead to the jump of temperature, electromagnetic force, and stress intensity factor. In addition, the sensitivity of flux-jump and fracture behaviors to different parameters and the influence of flux jump on the demagnetization behavior under crossed magnetic fields are discussed. We also find the levitation force jumping phenomenon when the bulk sample is magnetized in a nonuniform magnetic field. From the results obtained, we provide some general guidelines on how the system parameters of superconducting bulk magnets could be chosen to improve the thermal-magnetic-mechanical stability.