E. B. Sonin

Multiwalled carbon nanotube: Luttinger versus Fermi liquid

We have measured

Magnus force in superfluids and superconductors

\mathrm{IV}

Effect of Klein tunneling on conductance and shot noise in ballistic graphene

curves of multiwalled carbon nanotubes using end contacts. At low voltages, the tunneling conductance obeys non-Ohmic power law, which is predicted both by the Luttinger liquid and the environment-quantum-fluctuation theories. However, at higher voltages we observe a crossover to Ohms law with a Coulomb-blockade offset, which agrees with the environment-quantum-fluctuation theory, but cannot be explained by the Luttinger-liquid theory. From the high-voltage tunneling conductance we determine the transmission line parameters of the nanotubes.

Vortex Fluctuations, Negative Hall Effect, and Thermally Activated Resistivity in Layered and Thin-Film Superconductors in an External Magnetic Field

The forces on the vortex, transverse to its velocity, are considered. In addition to the superfluid Magnus force from the condensate (superfluid component), there are transverse forces from thermal quasiparticles and external fields violating the Galilean invariance. The forces between quasiparticles and the vortex originate from interference of quasiparticles with trajectories on the left and on the right from the vortex like similar forces for electrons interacting with the thin magnetic-flux tube (the Aharonov-Bohm effect). These forces are derived for phonons from the equations of superfluid hydrodynamics, and for BCS quasiparticles from the Bogolyubov{endash}de Gennes equations. The effect of external fields breaking Galilean invariance is analyzed for vortices in the two-dimensional Josephson junction array. The symmetry analysis of the classical equations for the array shows that the total transverse force on the vortex vanishes. Therefore the Hall effect which is linear in the transverse force is absent also. This means that the Magnus force from the superfluid component {ital exactly} cancels with the transverse force from the external fields. The results of other approaches are also brought together for discussion. {copyright} {ital 1997} {ital The American Physical Society}

Dynamics of helical vortices and helical-vortex rings

The conductance and the Fano factor in a graphene sheet in the ballistic regime are calculated. The electrostatic potential in the sheet is modeled by a trapezoid barrier, which allows one to use the exact solution of the Dirac equation in a uniform electric field in the slope areas (the two lateral sides of the trapezoid). Asymmetry with respect to the sign of the gate voltage manifests the difference between the Klein tunneling and the overbarrier transmission. The phase coherence between Klein-tunneling events in the slope areas (

Comment on “Ferromagnetic film on a superconducting substrate”

p\text{\ensuremath{-}}n

Proposal for measuring mechanically equilibrium spin currents in the rashba medium.

transitions) leads to conductance and Fano-factor oscillation at high negative gate voltages. The comparison of the developed theory with the experiment supports the conclusion that the Klein tunneling was revealed experimentally.

Charge transport and shot noise in a ballistic graphene sheet

The thermally activated resistivity, rxx, and the negative Hall resistivity, rxy are explained as two consequences of the same effect, namely the unbinding of vortex pairs in the vicinity of Tc. Both rxx and rxy exhibit a thermally activated behaviour. The activation energy depends logarithmically on the magnetic field. Our explanation suggests rxy ~ rxxa with a = 1 in accordance with recent measurements.

Equilibrium spin currents in the Rashba medium

The letter considers dynamics of helical vortices and helical-vortex rings either solving directly the equations of motions of a vortex line or using canonical relations following from the Hamiltonian equations of motion. An analytical solution in elliptical integrals was found for helical-vortex rings in the local-induction approximation. The analysis based on the canonical Hamilton relation provides a clear physical explanation for anomalous velocities of helical-vortex rings, i.e., for suppression of the velocity and even inversion of its direction at sufficiently large amplitude of the helical distortion. The extended local-induction approximation is suggested, which provides an exact solution for the equations of motion of helical vortices and helical-vortex rings in the limit when the small-pitch helical vortex reduces to a cylindric sheet of uniform vorticity.

Spontaneous vortex phase and the Meissner-state in the magneto- superconductor Eu1.5Ce0.5RuSr2Cu2O10−δ(Eu-2122)

A superconducting substrate is not able to shrink drastically domains in a ferromagnetic film, contrary to the prediction of Bulaevskii and Chudnovsky [Phys. Rev. B, 63, issue1 (2001)]. This is shown on the basis of the exact solution for the stripe domain structure.