arXiv subjects

V. M. Loktev

Publications and source records attributed to V. M. Loktev.

58 records · Page 4Linked to original sources

arXiv1997

Phase diagram in 2D Fröhlich model of metal at arbitrary carrier density: pseudogap versus doping

It is shown that in 2D system of the fermions with simplest indirect boson-induced attraction (through the Einstein phonon exchange as an example) along with the normal and superconducting phases there arises a new (called "abnormal normal" or pseudogap) one where the absolute value of the order parameter is finite but its phase is a random quantity. It is important that this new phase really exists at low carriers density only, i.e. it shrinks when doping increases. The relevance of the results obtained with dependence of pseudogap on doping in high-temperature superconductors is speculated.

cond-mat.supr-con↗

arXiv1996

Crossover from BCS to Composite Boson (Local Pair) Superconductivity in Quasi-2D systems

The crossover from cooperative Cooper pairing to independent bound state (composite bosons) formation and condensation in quasi-2D systems is studied. It is shown that at low carrier density the critical superconducting temperature is equal to the temperature of Bose-condensation of ideal quasi-2D Bose-gas with heavy dynamical mass, meanwhile at high densities the BCS result remains valid. The evident nonmonotoneous behaviour of the critical temperature as function of the coupling constant (the energy of the two particle bound state) is a qualitative difference of quasi-2D crossover from 3D one.

cond-mat↗

arXiv1995

On the normal phase of 2D Fermi liquid with weak attraction between particles

Proceeding from the simplest field theoretical model of 2D metal, the normal phase Green functions of the weakly interacting fermions and the order parameter fluctuations (responsible for the attraction between fermions) are obtained. It is shown that taking into consideration the fluctuations mentioned leads to a considerable reduction of the fermion wave function renormalization constant (quasiparticle weight) as well as to a linear dependence of the quasiparticle damping on the temperature. A general dependence of 2D Fermi liquid properties on the fermion density is discussed. The relevance of the proposed model to the marginal behavior of the Fermi liquid of high--$T_c$ superconductors, in particular, to their linear temperature dependence of the resistivity is indicated.

cond-mat↗

arXiv1995

On the Superconductivity of 2D System with Arbitrary Carrier Density in External Magnetic Field

Selfconsistent equations which describe the order parameter and chemical potential behaviour in $2D$ metalic system as functions of external magnetic field, $H$, temperature, $T$, and carrier density, $n$, are obtained. It is shown that for the case of the local pairs (low carrier density and negative chemical potential $μ$) the derivative $dH_{c_2}(T)/dT$ at $T=T_c$ is essentially less then that for the system with Cooper pairs (high carrier density and positive chemical potential $μ\gg T_c$). It is found that in magnetic field satisfying the quantum limit criterium the system is characterized by non-trivial inhomogeneuos order parameter which can exist at rather high temperatures.

cond-mat↗