V. M. Loktev

Electrical conductivity in graphene with point defects

Received 7 May 2010; revised manuscript received 1 July 2010; published 24 August 2010The electrical conductivity of graphene containing point defects is studied within the binary alloy model inits dependence on the Fermi-level position at the zero temperature. It is found that the minimal conductivityvalue does not have a universal character and corresponds to the impurity resonance energy rather than to theDirac point position in the spectrum. The substantial asymmetry of the resulting dependence of the conduc-tivity on the gate-voltage magnitude is attributed as well to the very shift of the conductivity minimum to theresonance state energy.DOI: 10.1103/PhysRevB.82.085436 PACS number s : 71.23. k, 71.55. i, 81.05.ue

Aharonov-Bohm effect in relativistic and nonrelativistic two-dimensional electron gases: A comparative study

We carry out a comparative study of electronic properties of 2D electron gas (2DEG) in a magnetic field of an infinitesimally thin solenoid with relativistic dispersion as in graphene and quadratic dispersion as in semiconducting heterostructures. The problem of ambiguity of the zero mode solutions of the Dirac equation is treated by considering of a finite radius flux tube which allows to select unique solutions associated with each

Density of states of relativistic and nonrelativistic two-dimensional electron gases in a uniform magnetic and Aharonov-Bohm fields

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Temperature-doping phase diagram of layered superconductors

point of graphenes Brillouin zone. Then this radius is allowed to go to zero. On the base of the obtained in this case analytical solutions in the Aharonov-Bohm potential the local and total density of states (DOS) are calculated. It is shown that in the case of graphene there is an excess of LDOS near the vortex, while in 2DEG the LDOS is depleted. This results in excess of the induced by the vortex DOS in graphene and in its depletion in 2DEG. We discuss the application of the results for the local density of states for the scanning tunneling spectroscopy done on graphene.

Crossover from superfluidity to superconductivity in a system with doping dependent attraction

We study the electronic properties of two-dimensional electron gas (2DEG) with quadratic dispersion and with relativistic dispersion as in graphene in the inhomogeneous magnetic field consisting of the Aharonov-Bohm flux and a constant background field. The total and local density of states (LDOS) are obtained on the base of the analytic solutions of the Schrodinger and Dirac equations in the inhomogeneous magnetic field. It is shown that as it was in the situation with a pure Aharonov-Bohm flux, in the case of graphene there is an excess of LDOS near the vortex, while in 2DEG the LDOS is depleted. This results in excess of the induced by the vortex DOS in graphene and in its depletion in 2DEG.

Order parameter fluctuations and superconducting transition temperature in quasi-2D metals with arbitrary carrier density

The superconducting properties of a layered system are analyzed for the cases of zero and nonzero angular momenta of the pairs. The effective thermodynamic potential for the quasi-two-dimensional XY model for the gradients of the phase of the order parameter is derived from the microscopic superconducting Hamiltonian. The dependence of the superconducting critical temperature T c on doping, or carrier density, is studied at different values of coupling and interlayer hopping. It is shown that the critical temperature T c of the layered system can be lower than the critical temperature of the two-dimensional Berezinskii-Kosterlitz-Thouless transition T B K T at some values of the model parameters, contrary to the case in which the parameters of the XY model do not depend on the microscopic Hamiltonian parameters.

Electronic density of states for two-dimensional system in uniform magnetic and Aharonov–Bohm fields

Zero temperature crossover from superfluidity to superconductivity with carrier density increasing is studied for a two-dimensional system in the s-wave and d-wave pairing channels. It was assumed that the particle attraction correlation length depends on carrier density

Superconducting properties of the 2D models with different types of inter-particle coupling

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Peculiarities of superconductivity in 2D metals: transition from Cooper pairing to local pairing

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On phase states appearing in layered copper oxides under doping (On the 90th anniversary of B. G. Lazarev)

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