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O. P. Sushkov

Publications and source records attributed to O. P. Sushkov.

At least 109 records · Page 6Linked to original sources
arXiv1997

The bulk Josephson responce of the d-g-wave cuprate superconductor

We consider the implications of the small Fermi surface for the ab-plane microwave absorption. The small Fermi surface results in two superconducting condensates. Linear combinations of these condensates correspond to the d- and g-wave pairings. Microwave electric field applied in the ab-plane induces Josephson transitions between the condensates. Dependence of the absorption upon direction, amplitude and frequency of the external microwave field is calculated. Results of the calculation are compared with the observed recently novel non-linear phenomena in microwave absorption of $YBaCu_2O_{7-δ}$ single crystals.

cond-mat.supr-con↗
arXiv1997

Phase oscillations between two superconducting condensates in cuprate superconductors

Implications of the small Fermi surface are discussed. We demonstrate that superconductivity in this system can be described in terms of two coupled condensates. The two condensates result in a collective excitation corresponding to the relative phase oscillation - a phason. We discuss the possibility of searching for this collective excitation in the dynamic resistance of the SQUID.

cond-mat.supr-con↗
arXiv1997

The role of g-wave pairing and Josephson tunneling in high Tc superconductors

The implications of the two-pocket Fermi surface for macroscopic quantum phenomena are considered. We demonstrate that in the case of the two-pocket Fermi surface the g-wave pairing is closely related to the d-wave one. As a result two macroscopic condensates arise. The Josephson tunneling for such two-component system has very special properties. We prove that the presence of the g-wave does not contradict the existing experimental data on tunneling. We also discuss the possible ways to experimentally reveal the g-wave component.

cond-mat.supr-con↗
arXiv1996

Average over energy effect of parity nonconservation in neutron scattering on heavy nuclei

Using semiclassical approximation we consider parity nonconservation (PNC) averaged over compound resonances. We demonstrate that the result of the averaging crucially depends on the properties of residual strong nucleon-nucleon interaction. Natural way to elucidate this problem is to investigate experimentally PNC spin rotation with nonmonachromatic neutron beam: $E \sim ΔE \sim 1MeV$. Value of the effect can reach $ψ\sim 10^{-5}-10^{-4}$ per mean free path.

nucl-th↗
arXiv1996

Few interacting particles in a random potential

We study the localization length of few interacting particles in a random potential. Concentrating on the case of three particles we show that their localization length is strongly enhanced comparing to the enhancement for two interacting particles.

cond-mat↗
arXiv1996

Temperature dependence of the electron chemical potential in YBa2Cu3O

We study the behaviour of the electronic chemical potential in YBa2Cu3O near the superconducting transition using the spin-wave exchange theory of pairing. We find that the experimental value of the jump in the temperature derivative of the chemical potential is inconsistent with the theoretical value calculated under the assumption of constant hole concentration. It is suggested that charge transfer between chains and planes takes place and corresponding calculations are done.

cond-mat↗
arXiv1996

Hole photoproduction in insulating copper oxide

Basing on t-J model we calculate the k-dependence of a single hole photoproduction probability for CuO2 plane at zero doping. We also discuss the radiation of spin-waves which can substantially deform the shape of photoemission spectra.

cond-mat↗
arXiv1995

The incoherent part of the spin-wave polarization operator in the t-J model

A calculation of the spin-wave polarization operator is very important for the analysis of the magnetic structure of high temperature superconductors. We analyze the significance of the incoherent part of the spin-wave polarization operator within the framework of the t-J model. This part is calculated analytically for small doping with logarithmic accuracy. We conclude that the incoherent part of the spin-wave polarization operator is negligible in comparison with the coherent part.

cond-mat↗
arXiv1995

Spin-wave condensation and quantum melting of long-range antiferromagnetic order in t-J model

Ground state wave function of two-dimensional t-J model is found at doping close to half filling. It is shown that the condensation of Cooper pairs (superconducting pairing of mobile holes) and the condensation of spin-waves into spin-liquid state are closely connected. The effective spectrum of $S=1$ excitations, spin-wave gap pseudo-gap $Δ_M$, magnetic correlation length $ξ_M$, and static magnetic formfactor $S_M(\bf q)$ are calculated.

cond-mat↗
arXiv1995

Many Body Correlation Corrections to Superconducting Pairing in Two Dimensions.

We demonstrate that in the strong coupling limit (the superconducting gap $Δ$ is as large as the chemical potential $μ$), which is relevant to the high-$T_c$ superconductivity, the correlation corrections to the gap and critical temperature are about 10\% of the corresponding mean field approximation values. For the weak coupling ($Δ\ll μ$) the correlation corrections are very large: of the order of 100\% of the corresponding mean field values.

cond-mat↗
arXiv1995

Two-hole bound states in modified t-J model

We consider modified $t-J$ model with minimum of single-hole dispersion at the points $(0,\pm π)$, $(\pm π,0)$. It is shown that two holes on antiferromagnetic background produce a bound state which properties strongly differs from the states known in the unmodified $t-J$ model. The bound state is d-wave, it has four nodes on the face of the magnetic Brillouin zone. However, in the coordinate representation it looks like as usual s-wave.

supr-con↗
arXiv1995

Hole-hole superconducting pairing in the t-J model induced by spin-wave exchange

We study numerically the hole pairing induced by spin-wave exchange. The contact hole-hole interaction is taken into account as well. It is assumed that antiferromagnetic order is preserved at all scales relevant to pairing. The strongest pairing is obtained for the d-wave symmetry of the gap. Dependence of the value of the gap on hole concentration and temperature is presented. For the critical temperature we obtain Tc about 100 K at the hole concentration delta = 0.2-0.3.

cond-mat↗
arXiv1994

Large size two-hole bound states in t-J model

Several series of shallow large-size ($l \gg lattice~ spacing$) two-hole bound states are found in the two-dimensional t-J model. Their binding energies depend exponentially on the inverse value of the hole-spin-wave coupling constant. Their parity is connected with the angular wave function in a nonstandard way. The possible role of these states in the formation of superconducting pairing is considered.

cond-mat↗
arXiv1994

The hole-hole superconducting pairing in t-J model induced by the long-range spin-wave exchange

Long-range $(r \sim p_F^{-1} \gg lattice \ spacing)$ spin-wave exchange produces a very strong pairing of the holes. The different symmetry solutions of BCS-type equation for the superconducting gap $Δ$ are found. The most strong pairing corresponds to $d$-wave symmetry. The physical reasons for the strong pairing are: 1)large velocity of the spin-wave, 2) a ``collapse'' effect in the attractive potential (-1/r^2) describing the interaction between two holes induced by spin-wave exchange. 3)strongly asymmetric hole dispersion. At concentration of the holes $δ\sim 0.01-0.3$ we get $Δ\sim T_c \sim ε_F$. At very low concentration of the holes the many-body wave function of the ground state decays into the product of two-hole bound states.

cond-mat↗