E. Šimánek

Infinite susceptibility without long-range order: The 1n2 planar chain

Abstract We consider a one-dimensional chain of classical plane rotors with ferromagnetic interactions decaying as 1 n 2 . The spin correlation function shows a power-law decay and the susceptibility diverges at low temperatures, although there is no spontaneous magnetization. The implications for the transition to ohmic conduction, in an equivalent model of the tunnel junction, are discussed.

Charging fluctuations and resistive transition in Josephson junction arrays

Abstract The density of a vortex plasma in a two-dimensional quantum planar model is calculated as a function of temperature. The results imply flux-flow resistance with tails extending down to T = 0 and allowing for the possibility of resistance minima.

Nuclear spin--lattice relaxation in small superconducting particles.

Abstract A calculation of nuclear spin-lattice relaxation in zero-dimensional superconductors is described which uses the renormalization procedure of Abrahams et al. and Patton. The results agree with measurements of Kobayashi and co-workers on fine aluminum particles.

Fluxon dissipation in a viscoelastic superconductor

Abstract The dissipation of the dynamic stresses surrounding a fluxon in a viscoelastic superconductor is shown to produce a significant contribution to the viscosity of a fluxon. Disorder-induced relaxation in glassy superconductors is shown to lead to a velocity dependent fluxon viscosity.

Barrier noise and flux creep in high-Tc superconductors

Abstract We calculate the rate of thermal activation of flux lines over a barrier exhibiting time-dependent fluctuations of the activation energy. Strong deviations from the linear T -dependence of the rate are predicted in the low temperature region, where the barrier fluctuations are of quantum nature.

Dynamic order parameter susceptibility in inhomogeneous superconductors

Abstract A self-consistent calculation of the configurational average of dynamic susceptibility in inhomogeneous superconductor predicts a behavior of the renormalized relaxation rate in agreement with experiment and in disagreement with conventional slowing down.

Quantum dynamics of vortices in superconducting layers. Role of fermion bound states

Abstract The effective Euclidean action for a vortex in a superconducting layer is obtained microscopically as a functional of vortex position. At T =0, the dynamics is dominated by transitions between the lowest energy core bound states. In a clean superconductor, these transitions are responsible for an anomalously large inertial mass of the vortex. The Hall-force contribution to the action is of the same order of magnitude as in a classical superfluid. Dissipation tends to reduce the Hall force, and it leads to an ohmic-like action modified by the splitting between the core states.

Anomalous specific heat and nuclear spin relaxation in Al-transition metal alloys☆

Abstract A mechanism involving dislocation pinning by impurities is proposed to explain the anomalous lattice specific heat and the nuclear spin—lattice relaxation in Al—transition metal alloys.

Thermally activated hopping in granular films and powders

Abstract A mechanism involving carrier-carrier interaction is proposed for intergrain hopping of electrons in thin films and fine particle powders. The calculated hopping rate yields large broadening of electron levels in fine particle samples.

Collective modes in superconductors near Tc

Abstract A phonon-like critical mode is obtained in superconductors near T c as a result of screening due to electron-lattice ion interaction.