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608 results on '"Abd-Shukor, R."'

12. Theory of d-wave high temperature superconductivity in the cuprates involving non-linear lattice modes

Author

Lee, B. S., Yoon, T. L., and Abd-Shukor, R.

Subjects
Condensed Matter - Superconductivity
Abstract

The transition mechanism in high temperature cuprate superconductors is an outstanding puzzle. A previous suggestion on the role of non-linear local lattice instability modes on the microscopic pairing mechanism in high temperature cuprate superconductors \cite{Lee:JSNM09} is re-examined to provide a viable mechanism for superconductivity in these cuprates via an unusual lattice vibration in which an electron is predominantly interacting with a nonlinear $Q_2$ mode of the oxygen clusters in the CuO$_2$ planes. It is shown that the interaction has explicit d-wave symmetry and leads to an indirect coupling of d-wave symmetry between electrons. As a follow-up of \cite{Lee:JSNM09}, in this paper, we report detailed derivation of the superconducting gap equation and numerical solutions for the transition temperature as inherently integrated into the so-called Extended Hubbard Model (EHM). A unique feature in the EHM is that the transition temperature has an inherent k-dependence. In addition, superconducting gap solutions are restrained to specific regions in the first Brillouin zone (1BZ). It is very feasible to expect that the EHM naturally inherits a huge parameter space in which experimentally measured results, such as the well-known superconducting dome and the phase diagram from electronic Raman scattering \cite{Sacuto:RPP13} can be accommodated. The EHM model hence offers a viable venue to search for or confirm any signature in k-point-sensitive experimental measurements., Comment: Manuscript submitted to Journal of Superconductivity and Novel Magnetism

Published
2017

19. Effect of copper (II) sulfide addition on the transport critical current density and AC susceptibility of Bi1.6Pb0.4Sr2Ca2Cu3O10 superconductor.

Author

Ilhamsyah, A. B. P., Zabidi, Nurin Afifah Mohd, Hashidi, Muhammad Amirul Hakimi, Suib, Nurul Raihan Mohd, Mahat, A. M., Abd-Shukor, R., and Masnita, M. J.

Subjects
COPPER sulfide, CRITICAL currents, SUPERCONDUCTIVITY, X-ray diffraction, SUPERCONDUCTORS, FLUX pinning, COPPER
Abstract

The effect of copper (II) sulfide (CuS) addition on the superconductivity of (Bi1.6Pb0.4)Sr2Ca2Cu3O10 (CuS)x (x = 0–1.5 wt%) is reported. All samples were prepared via the co-precipitation technique. The XRD patterns revealed that the formation of Bi-2223 phase was not affected by the CuS addition. The temperature-dependent resistance measurements showed a metallic normal state behavior for all samples, with onset transition temperatures Tc onset between 109 and 118 K and zero transition temperatures Tc zero between 96 and 101 K. The intragranular and intergranular diamagnetic transition, intrinsic and coupling peak temperatures, the onset temperature of grain decoupling and the Josephson phase-locking temperature of (Bi1.6Pb0.4)Sr2Ca2Cu3O10 were not suppressed at lower CuS additions (x ≤ 0.2 wt%) but further CuS additions (x = 0.8–1.5 wt%) severely suppressed these properties. The highest Josephson current (10.82 μA) and Josephson energy coupling (22.22 meV) were exhibited by the non-added sample. The volume fraction of the grains decreased when CuS was added which indicated that the intergranular contribution was enhanced as shown by the AC susceptibility curves for all added samples. The highest transport critical current density, Jct at 40 K was for x = 0.2 wt% sample (4713 mA cm−2). The effect of internal lattice strain on the transition temperatures was also discussed. This work showed that lower addition of CuS could enhance the connectivity between the grains and enhance flux pinning. [ABSTRACT FROM AUTHOR]

Published
2024
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49. AC susceptibility and electrical properties of Cr and Mo substituted Tl(BaSr)CaCu2O7 Tl-1212 type phase superconductors.

Author

Muhammad-Najib, K., Muhammad-Aizat, K., Jumali, M. H., and Abd-Shukor, R.

Subjects
FIELD emission electron microscopes, SUPERCONDUCTORS, TRANSITION temperature, CHROMIUM, LATTICE constants
Abstract

The Ba and Sr bearing Tl(BaSr)CaCu2O7 (Tl-1212) phase is an interesting superconductor. Optimizing the average copper valence can lead to a high transition temperature, Tc. Single elemental substitution can be used to optimize the Cu valence. This work investigated the effects of multivalent Cr and Mo substitutions at the Tl site of Tl1-xMx(BaSr)CaCu2O7 (M = Cr and Mo). The samples were prepared via the solid-state reaction method. The structure and lattice parameters were determined using the X-ray diffraction method (XRD). A field emission scanning electron microscope (FESEM) was utilized to observe the microstructure. The electrical resistance and AC susceptibility were measured to determine the transition temperature. XRD pattern showed a single Tl(BaSr)CaCu2O7 phase for the non-substituted sample. Other phases, such as Tl-1201 and Ca0.3Sr0.7CuO2 were also observed in the Cr and Mo substituted samples. The non-substituted sample showed onset transition temperature, Tc-onset of 108 K. The highest Tc-onset was observed in the Tl0.9Mo0.1(BaSr)CaCu2O7 (115 K) and Tl0.5Cr0.5(BaSr)CaCu2O7 (111 K) samples. The intergranular critical current density was between 17 and 22 A cm−2. Cr substitutions for x = 0.1 to 0.5 and Mo substitutions for x = 0.1 showed the highest transition temperature. These results can be used as guides to improve the superconducting properties of the Tl-1212 phase. [ABSTRACT FROM AUTHOR]

Published
2023
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