109 research outputs found
Behaviour of superconductivity energetic characteristics in electron-doped cuprates. A simple model
A simple model to describe the energetic phase diagram of electron-doped
cuprate superconductor is developed. Interband pairing operates between the UHB
and the defect states created by doping and supplied by both extincting HB-s.
Two defect subbands correspond to the () and () momentum
regions. Extended doping quenches the bare normal state gaps (pseudogaps).
Maximal transition temperature corresponds to overlapping bands ensemble
intersected by the chemical potential. Illustrative results for , pseudo-
and superconducting gaps are calculated on the whole doping scale. Major
characteristics features on the phase diagram are reproduced. Anticipated
manifestation of gaps doping dynamics is discussed.Comment: 10 pages, 3 figure
Dependence of the superconducting effective mass on doping in cuprates
Using a doping-determined multiband model spectrum of a "typical'' cuprate
the effective mass of the paired carriers is calculated on the whole doping
scale. Large values quench rapidly with leaving the very underdoped
region. Further slower diminishing of reproduces the trend towards
restoring the Fermi-liquid behaviour in cuprates with progressive doping. The
interband superconducting condensate density () shows similar behaviour to
the transition temperature and superconducting gaps. The ratio
has an expressed maximum close to optimal doping as also the thermodynamic
critical field. All the overlapping band components are intersected by the
chemical potential at this. The pairing strength and the phase coherence
develop simultaneously. In spite of its simplicity, the model describes the
behaviour of various cuprate characteristics on the doping scale.Comment: 9 pages, 5 figure
On the interband pairing in doped graphane
An estimation shows that the interband pairing channel between the valence
band components of doped graphane can support a superconducting transition
temperature (or a contribution into this expected event) of the order of 100 K
at the coupling strength near 1 eV
Analytic and geometric properties of photoinduced effects in noncentrosymmetric crystals: photovoltaic current and optical rectification
An original dispersion relation between the stationary coherent nonlinear
optical responses by current and polarisation is obtained. The dispersion
relation provides a new complimentary tool that can be employed to study
light-induced charge transport models and facilitate experimental data
analysis. It is shown that the origin of the coherent current and the
dc-polarisation induced in a noncentrosymmetric crystal under illumination is
related to the theory of the Berry phase and can be represented in terms of the
renormalised geometric potentials. This renormalisation originates from the
extra phase difference acquired by a carrier in the light field on the quantum
transition between the electronic bands. The gauge invariance of the
corresponding expressions for the current and the polarisation is demonstrated.Comment: 7 page
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