Biomedical subjects

I V Gornyi

Publications and source records attributed to I V Gornyi.

7 recordsLinked to original sources

PubMed2005

Interacting electrons in disordered wires: Anderson localization and low-T transport.

We study the conductivity sigma(T) of interacting electrons in a low-dimensional disordered system at low temperature T. For weak interactions, the weak-localization regime crosses over with lowering T into a dephasing-induced "power-law hopping." As T is further decreased, the Anderson localization in Fock space crucially affects sigma(T), inducing a transition at T = T(c), so that sigma(T < T(c)) = 0. The critical behavior of sigma(T) above T(c) is ln sigma(T) proportional to -(T - T(c))(-1/2). The mechanism of transport in the critical regime is many-particle transitions between distant states in Fock space.

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PubMed2005

Dephasing and weak localization in disordered Luttinger liquid.

We study the transport properties of interacting electrons in a disordered quantum wire within the framework of the Luttinger liquid model. The conductivity at finite temperature is nonzero only because of inelastic electron-electron scattering. We demonstrate that the notion of weak localization is applicable to the strongly correlated one-dimensional electron system. We calculate the relevant dephasing rate, which for spinless electrons is governed by the interplay of electron-electron interaction and disorder, thus vanishing in the clean limit.

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PubMed2003

Loschmidt echo and Lyapunov exponent in a quantum disordered system.

We investigate the sensitivity of a disordered system with diffractive scatterers to a weak external perturbation. Specifically, we calculate the fidelity M(t) (also called the Loschmidt echo) characterizing a return probability after a propagation for a time t followed by a backward propagation governed by a slightly perturbed Hamiltonian. For short-range scatterers, we perform a diagrammatic calculation showing that the fidelity decays first exponentially according to the golden rule, and then follows a power law governed by the diffusive dynamics. For long-range disorder (when the diffractive scattering is of small-angle character), an intermediate regime emerges where the diagrammatics is not applicable. Using the path-integral technique, we derive a kinetic equation and show that M(t) decays exponentially with a rate governed by the classical Lyapunov exponent.

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PubMed2003

Interaction-induced magnetoresistance: from the diffusive to the ballistic regime.

We study interaction-induced quantum correction deltasigma(alphabeta) to the conductivity tensor of electrons in two dimensions for arbitrary Ttau, where T is the temperature and tau the transport mean free time. A general formula is derived, expressing deltasigma(alphabeta) in terms of classical propagators ("ballistic diffusons"). The formalism is used to calculate the interaction contribution to the magnetoresistance in a classically strong transverse field and smooth disorder in the whole range of temperatures from the diffusive (Ttau<<1) to the ballistic (Ttau greater, similar 1) regime.

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PubMed2002

Wave function correlations on the ballistic scale: exploring quantum chaos by quantum disorder.

We study the statistics of wave functions in a ballistic chaotic system. The statistical ensemble is generated by adding weak smooth disorder. The conjecture of Gaussian fluctuations of wave functions put forward by Berry [J. Phys. A 10, 2083 (1977)] and generalized by Hortikar and Srednicki [Phys. Rev. Lett. 80, 1646 (1998); Phys. Rev. E 57, 7313 (1998)] is proven to hold on sufficiently short distances, while it is found to be strongly violated on larger scales. This also resolves the conflict between the above conjecture and the wave function normalization. The method is further used to study ballistic correlations of wave functions in a random magnetic field.

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PubMed2001

Nesting symmetries and diffusion in disordered d-wave superconductors.

The low-energy density of states (DOS) of disordered 2D d-wave superconductors is extremely sensitive to details of both the disorder model and the electronic band structure. Using diagrammatic methods and numerical solutions of the Bogoliubov--de Gennes equations, we show that the physical origin of this sensitivity is the existence of a novel diffusive mode with momentum close to (pi,pi) which is gapless only in systems with a global nesting symmetry. We find that in generic situations the DOS vanishes at the Fermi level. However, proximity to the highly symmetric case may nevertheless lead to observable nonmonotonic behavior of the DOS in the cuprates.

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PubMed2001

Interacting random Dirac fermions in superconducting cuprates.

We study the effects of quasiparticle interactions on disorder-induced localization of Dirac-like nodal excitations in superconducting high- Tc cuprates. As suggested by the experimental angle-resolved photoemission spectroscopy and terahertz conductivity data in Bi2Sr2CaCu2O(8+delta), we focus on the interactions mediated by the order parameter fluctuations near an incipient second pairing transition d --> d + is(id'). We find interaction corrections to the density of states, specific heat, and conductivity as well as phase and energy relaxation rates and assess the applicability of the recent localization scenarios for noninteracting random Dirac fermions to the cuprates.

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