High-Tc Materials. Atomic, Mesoscopic and Optical Physics. Biological and Soft Systems. High Energy Physics. NanoPhotonics. Optoelectronics. Microelectronics. Molecular Engineering. Quantum Matter. Anisotropic Superconductivity. ceramics. ceramic conductors are the so-called high Tc superconductors, materials that lose their resistance at much higher critical temperatures than their metal alloy counterparts. Most high Tc ceramics are layered structures, with two-dimensional copper-oxygen sheets along which superconduction takes place. The label high-Tc may be reserved by some authors for those with critical temperature greater than However, cuprate materials are brittle ceramics which are.
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Some of the research in the group has been directed at studying the specific heat of the high-Tc's in the pseudogap region of the phase diagram. A second intriguing question surrounds how the high-Tc's evolve with charge carrier concentration dopingmoving from an antiferromagnetically ordered insulator at low doping, to an unconventional superconductor and eventually a Fermi liquid metal at higher doping.
At low dopings, there is evidence for a high tc materials behaviour of electronic spins, and part of the research effort high tc materials directed towards exploring this region of the phase diagram through muon-spin relaxation, transport and dielectric measurements.
The phases shown are the antiferromagnetic AF phase close to zero doping, the superconducting phase around optimal doping, and the high tc materials phase.
Doping ranges possible for some common compounds are also shown. Neighbouring layers containing ions such as lanthanumbariumhigh tc materialsor other atoms act to stabilize the high tc materials and dope electrons or holes onto the copper-oxide layers.
The undoped "parent" or "mother" compounds are Mott insulators with long-range antiferromagnetic order at low enough temperature. Single band models are generally considered to be sufficient to describe the electronic properties.
High-temperature superconductivity - Wikipedia
The cuprate superconductors adopt a perovskite structure. Chemical formulae of superconducting materials generally contain fractional numbers to describe the doping required for superconductivity.
There are several families of cuprate superconductors and they can be categorized by the elements they contain and the number of adjacent copper-oxide layers in each high tc materials block.
Possible mechanisms for superconductivity in the cuprates are still the subject of considerable debate and further research. Certain aspects common to all materials have been identified.
High-Tc Materials — Department of Physics
Recent work on the Fermi surface has shown that nesting occurs at four points high tc materials the antiferromagnetic Brillouin zone where spin waves exist and that the superconducting energy gap is larger at these points.
The weak isotope effects observed for most cuprates contrast with conventional superconductors that are well described by BCS theory. Similarities and differences in the properties of hole-doped and electron doped cuprates: Presence of a pseudogap phase up to at least optimal doping.
Different trends in the Uemura plot relating transition temperature to the superfluid high tc materials. The inverse square of the London penetration depth appears to be proportional to the critical temperature for a large number of underdoped cuprate superconductors, but the constant of proportionality is different for hole- and electron-doped cuprates.
The linear trend implies that the physics of these materials is strongly two-dimensional.
Universal hourglass-shaped feature in the spin excitations of cuprates measured using inelastic neutron diffraction. Nernst effect evident in both the superconducting and pseudogap phases.
High-Tc superconductor | physics |
The dashed rectangle represents the first Brillouin zone. Therefore, the Fermi surface of HTSC high tc materials very close to the Fermi surface of the doped CuO2 plane or multi-planes, in case of multi-layer cuprates and can be presented on the 2D reciprocal space or momentum space of the CuO2 lattice.
It can high tc materials derived from the band structure calculations or measured by angle resolved photoemission spectroscopy ARPES. In a wide range of charge carrier concentration doping levelin which the hole-doped HTSC are superconducting, the Fermi surface is hole-like i.
This results in an inherent in-plane anisotropy of the electronic properties of HTSC. Iron-based superconductor Simplified doping dependent phase diagrams high tc materials iron-based superconductors for both Ln and Ba materials.
The Ln phase diagrams for La  and Sm   were determined using muon spin spectroscopythe phase diagram for Ce  was determined using neutron diffraction. The Ba phase high tc materials is based on.
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This is currently the family with the second highest critical temperature, behind the cuprates. These materials superconduct close to high tc materials composition and are referred to as compounds.
Strong evidence that the Tc value varies with the As-Fe-As bond angles has already emerged and shows that the optimal Tc value is obtained with undistorted FeAs4 tetrahedra.
When cooled below a critical temperature this high-pressure phase exhibits superconductivity.