نتایج جستجو برای: superconducting energy gap
تعداد نتایج: 812569 فیلتر نتایج به سال:
In conventional BCS superconductors, the quantum condensation of superconducting electron pairs is understood as a Fermi surface instability, in which the low-energy electrons are paired by attractive interactions. Whether this explanation is still valid in high-Tc superconductors such as cuprates and iron-based superconductors remains an open question. In particular, a fundamentally different ...
Unconventional superconductors such as the high-transition temperature (Tc) cuprates, heavy-fermion systems and iron arsenide-based compounds exhibit antiferromagnetic fluctuations that are dominated by a resonance, a collective spinone excitation mode in the superconducting state. Here we demonstrate the existence of a universal linear relation, Er ∝ 2Δ , between the magnetic resonance energy ...
The electron transport though ferromagnetic-metal–superconducting hybrid devices is considered in the nonequilibrium Green’s function formalism in the quasiclassical approximation. Attention is focused on the limit in which the exchange splitting in the ferromagnet is much larger than the superconducting energy gap. Transport properties are then governed by an interplay between spin accumulatio...
Title of Dissertation: TUNNELING AND RAMAN SPECTROSCOPIES OF THE ELECTRON-DOPED HIGH-TEMPERATURE SUPERCONDUCTORS Muhammad Mumtaz Qazilbash, Doctor of Philosophy, 2004 Dissertation directed by: Professor Richard L. Greene Department of Physics This thesis consists of spectroscopic studies of the electron-doped high temperature cuprate superconductors Pr2−xCexCuO4−δ (PCCO) and Nd2−xCexCuO4−δ (NCC...
The recent discovery of superconductivity in MgB2, with its BCS-like Cooper pairing mechanism and the 40-K critical temperature, and the demonstration of efficient single-optical-photon detection in superconducting NbN nanowire meanders inspired an interest in the development of superconducting radiation detectors based on MgB2. We report the results of our experimental and theoretical studies ...
Semiconductor nanowires provide promising low-dimensional systems for the study of quantum transport phenomena in combination with superconductivity. Here we investigate the competition between the Coulomb blockade effect, Andreev reflection, and quantum interference, in InAs and InP nanowires connected to aluminum-based superconducting electrodes. We compare three limiting cases depending on t...
The recent discovery of high-temperature superconductivity in iron-based compounds has attracted much attention. How to further increase the superconducting transition temperature (T(c)) and how to understand the superconductivity mechanism are two prominent issues facing the current study of iron-based superconductors. The latest report of high-T(c) superconductivity in a single-layer FeSe is ...
By means of the Lanczos method we analyze superconducting correlations in ultrasmall grains at fixed particle number. We compute the ground state properties and the excitation gap of the pairing Hamiltonian as a function of the level spacing δ. Both quantities turn out to be parity dependent and universal functions of the ratio δ/∆ (∆ is the BCS gap). We then characterize superconductivity in t...
We study the low-energy band structure of armchair and small-band-gap semiconducting carbon nanotubes with proximity-induced superconducting pairing when a spiral magnetic field creates strong effective spin-orbit interactions from the Zeeman term and a periodic potential from the orbital part. We find that gapless Dirac fermions can be generated by variation of a single parameter. For a small-...
We calculate corrections to the BCS gap equation caused by the interaction of electrons with the collective phase and amplitude modes in the superconducting state. This feedback reduces the BCS gap parameter, ∆, and leaves the critical temperature, Tc, unchanged. The feedback effect is proportional to (∆/EF ), where EF is the Fermi energy. This is a negligible correction for type-I superconduct...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید