Holographic superconductor in a deformed four-dimensional STU model

In this paper, we consider deformed STU model in four dimensions including both electric and magnetic charges. Using AdS/CFT correspondence, we study holographic superconductor and obtain transport properties like electrical and thermal conductivities. We obtain transport properties in terms of the black hole magnetic charge and interpret it as magnetic monopole of dual field theory. We find that presence of magnetic charge is necessary to have maximum conductivities, and existence of magnetic monopole with a critical charge (137 e) to reach the maximum superconductivity is important. Also, we show that thermal conductivity increases with increasing of magnetic charge. It may be concluded that the origin of superconductivity is magnetic monopole.Comment: 19 pages, 8 Figures. Accepted for publication in EPJ

The feasibility of correlation between superconductivity and magnetic monopole: Establishment of semi-classical electrodynamics projection, TKH topological theory and dynamic vortex models

In this paper, a feasibility of semi-classical electromagnetic description together with experimental data, T-K-H topological and dynamic models and theory of vortex considered to justify the relation between superconductivity phenomena and magnetic monopole. We find that the electromagnetic energy of magnetic monopole is in agreement with vortex energy in topological theory and it can get close to thermal energy at room temperature. Indeed, these models suggest that the origin of the hot superconductivity may be magnetic monopoles with QM-Cl = 137 e (magnetic charge in classical approach) or QM-Q =137/2 e (magnetic charge in quantum approach), and the electrical conductivity is related to the mobile monopole or vortices. This research shows that the electrical permittivity ({\epsilon}) and magnetic permeability ({\mu}) of matter have a key role in the superconductive properties. We propose that this model may justify the hot superconductivity properties.Comment: 24 pages, 5 figure

Comparison of Urea and Citric Acid Complexing Agents and Annealing Temperature Effect on the Structural Properties of - and -Alumina Nanoparticles Synthesized by Sol-Gel Method

A sol-gel method based on the Pechini process was used to synthesize different phases of alumina nanoparticles using a polymeric precursor with Aluminum nitrate. The emphasis was on investigating the effect of two different complexing agents, urea and citric acid, on the structural properties, particle size, and phase transformation during the heat treatment that was studied by XRD, TEM, SEM, BET, and FT-IR spectroscopy. The obtained results showed that particles do get fused together at high temperatures, and also the size of particles increases with the increase of annealing temperature. It was concluded that the size of α-alumina synthesized by urea was 10–15 nm, whereas the sample with citric acid yielded α-powder with particle size of 200 nm. Also, the resulting powder prepared by urea exhibited larger surface area (84.2 m2/gm−1) compared to citric acid (39.92 m2/gm−1) at