Sökning: "high-Tc superconductivity"
Visar resultat 11 - 15 av 16 avhandlingar innehållade orden high-Tc superconductivity.
11. Deviations from the London model in superconductors
Sammanfattning : Using Small-Angle Neutron Scattering (SANS) we have studied the flux line lattices of the first heavy-fermion superconductor to be discovered, CeCu2Si2, the well-known high-temperature superconductor YBa2Cu3O7, along with Ca-doped variants of this compound, and several topological superconductor candidates that have attracted a lot of attention in the last few years, such as PbTaSe2, Au2Pb and β-Bi2Pd.Unconventional superconductors, with pairing mechanisms and properties that are not accounted for within BCS theory, are a subject of continuing interest. LÄS MER
12. Quantum Mechanical Studies of Electron Transport Processes Including Superconductivity
Sammanfattning : Processes of electron transfer, charge and spin localization, and electron pair transfer have been studied on the basis of the Marcus model and with the help of accurate quantum chemical calculations. A vibrational model, based on the corrections to the Born-Oppenheimerapproximation, which applies in the case of a vanishing barrier in the Marcus model, has been proposed. LÄS MER
13. d-wave Josephson Junctions
Sammanfattning : The properties of d-wave YBCO Josephson junctions and dc-SQUIDs with high misorientation angles have beenstudied experimentally .The predominant d-wave symmetry of the pairing wavefunction in high-Tc superconductors has, to a large extent, beena hinderance in applications, but it also makes it possible to fabricate devices with novel properties that may be suitablefor applications in the quantum regime; one particulary interesting property is a strong second harmonic component in the current-phase relation ofjunctions with the electrodes oriented in a node-lobe arrangement; so-called 0-45 junctions. LÄS MER
14. Quasiparticles in the Quantum Hall Effect
Sammanfattning : The fractional quantum Hall effect (FQHE), discovered in 1982 in a two-dimensional electron system, has generated a wealth of successful theory and new concepts in condensed matter physics, but is still not fully understood. The possibility of having nonabelian quasiparticle statistics has recently attracted attention on purely theoretical grounds but also because of its potential applications in topologically protected quantum computing. LÄS MER
15. Intrinsic tunneling spectroscopy of low-Tc cuprate superconductors : Pseudogap, fluctuations and electrical doping
Sammanfattning : In this thesis, intrinsic tunneling and magnetic transport measurements of the cuprate superconductor Bi2+xSr2-yCuO6+δ (Bi-2201) are presented. The compound is characterized by a single-CuO2 plane, has a very low critical temperature Tc ~ 4K and a relatively low upper critical field Hc2 ~ 10T. LÄS MER
