3 research outputs found
Effect of nonmagnetic and magnetic impurities on the specific heat jump in anisotropic superconductors
The specific-heat jump at a critical temperature in an
anisotropic superconductor containing both potential and spin-flip scatterers
is calculated within a weak-coupling mean-field approximation. It is shown that
the presence of even a small amount of spin-flip scatterers in the sample leads
to a drastic change in the dependence of on in a disordered
-wave or a strongly anisotropic s-wave superconductor. The implications
for experimental tests for the presence of an s-wave admixture in the
superconducting order parameter of high- superconductors are discussed.Comment: 9 pages, 5 figure
Resonant electron transfer between quantum dots
An interaction of electromagnetic field with a nanostructure composed of two
quantum dots is studied theoretically. An effect of a resonant electron
transfer between the localized low-lying states of quantum dots is predicted. A
necessary condition for such an effect is the existence of an excited bound
state whose energy lies close to the top of the barrier separating the quantum
dots. This effect may be used to realize the reversible quantum logic gate NOT
if the superposition of electron states in different quantum dots is viewed as
the superposition of bits 0 and 1.Comment: 8 pages, 1 EPS-figure, submitted to Phys. Rev.
Critical temperature of an anisotropic superconductor containing both nonmagnetic and magnetic impurities
The combined effect of both nonmagnetic and magnetic impurities on the
superconducting transition temperature is studied theoretically within the BCS
model. An expression for the critical temperature as a function of potential
and spin-flip scattering rates is derived for a two-dimensional superconductor
with arbitrary in-plane anisotropy of the superconducting order parameter,
ranging from isotropic s-wave to d-wave (or any pairing state with nonzero
angular momentum) and including anisotropic s-wave and mixed (d+s)-wave as
particular cases. This expression generalizes the well-known Abrikosov-Gor'kov
formula for the critical temperature of impure superconductors. The effect of
defects and impurities in high temperature superconductors is discussed.Comment: 4 eps figure