1,420 research outputs found
Low-Energy Spin Dynamics of CuO Chains in YBa(2)Cu(3)O(6+x)
We study the spin fluctuation dynamics of Cu-O chains in the oxygen deficient
planes of YBa(2)Cu(3)O(6+x). The chains are described by a model including
antiferromagnetic interactions between the spins and Kondo-like scattering of
the oxygen holes by the copper spins. There are incommensurate spin
fluctuations along the direction of the chains. The dynamic structure factor of
this system is qualitatively different from that of a quasi one-dimensional
localized antiferromagnet due to the presence of itinerant holes. We compute
the dynamic structure factor that could be measured in neutron scattering
experiments.Comment: 2 pages, 2 eps figures, LT22 proceedings, phbauth style file include
Topological radical of Banach module
We introduce the concept of topological radical of a Banach module. This
closed submodule have two description: the as the intersection of ranges of
maximal contractive monomorphism (from outside) and as the union of ranges of
small morphisms (from inside). This concept is a functional analytic analogue
for radical of module over a unital ring and has the similar categorical
properties
Optical conductivity of unconventional charge density wave systems: Role of vertex corrections
The optical conductivity of a d-CDW conductor is calculated for electrons on
a square lattice and a nearest-neighbor charge-charge interaction using the
lowest-order conserving approximation. The spectral properties of the
Drude-like peak at low frequencies and the broad hump due to transitions across
the gap at large frequencies are discussed, also as a function of temperature
and of the second-nearest neighbor hopping term t'. We find that vertex
corrections enhance the d.c. conductivity, make the Drude peak narrower and
provide a smooth transition from a renormalized regime at low to the bare
theory at high frequencies. It is also shown that vertex corrections enhance
the temperature dependence of the restricted optical sum leading to a
non-negligible violation of the sum rule in the d-CDW state.Comment: 10 pages, 6 figure
- …