Alan T. Dorsey

Effect of phase fluctuations on the single-particle properties of underdoped cuprates

We study the effect of order parameter phase fluctuations on the single-particle properties of fermions in the underdoped cuprate superconductors using a phenomenological low-energy theory. We identify the fermion-phase field coupling as the Doppler shift of the quasiparticle spectrum induced by the fluctuating superfluid velocity and we calculate the effect of these fluctuations on the fermion self-energy. We show that the vortex pair unbinding near the superconducting transition causes a significant broadening in the fermion spectral function, producing a pseudogaplike feature. We also discuss the specific heat and show that the phase fluctuation effect is visible due to the short coherence length.

Transport properties and fluctuations in type-II superconductors near Hc2.

We study the flux-flow Hall effect and thermomagnetic transport near the upper critical field H c2 in extreme type-II superconductors starting from a suitable generalization of the time-dependent Ginzburg-Landau equations. We explicitly incorporate the effects of backflow into the calculations of the local electric field and current, which leads to a current that is properly divergenceless. The Hall conductivity calculated from this current agrees with other mean-field calculations that assume a uniform applied electric field (the Schmid-Caroli-Maki solution), thereby vindicating these simplified treatments

Viscoelastic Behavior of Solid

Over the last five years several experimental groups have reported anomalies in the temperature dependence of the period and amplitude of a torsional oscillator containing solid

^4

^4

He

He. We model these experiments by assuming that

Velocity Selection for Propagating Fronts in Superconductors

^4

Squeezing Superfluid from a Stone: Coupling Superfluidity and Elasticity in a Supersolid

He is a viscoelastic solid--a solid with frequency dependent internal friction. We find that while our model can provide a quantitative account of the dissipation observed in the torsional oscillator experiments, it only accounts for about 10% of the observed period shift, leaving open the possibility that the remaining period shift is due to the onset of superfluidity in the sample.

Disclination unbinding transition in quantum Hall liquid crystals

Using the time-dependent Ginzburg-Landau equations we study the propagation of planar fronts in superconductors, which would appear after a quench to zero applied magnetic field. Our numerical solutions show that the fronts propagate at a unique speed which is controlled by the amount of magnetic flux trapped in the front. For small flux the speed can be determined from the linear marginal stability hypothesis, while for large flux the speed may be calculated using matched asymptotic expansions. At a special point the order parameter and vector potential are {ital dual}, leading to an {ital exact} solution which is used as the starting point for a perturbative analysis. {copyright} {ital 1996 The American Physical Society.}

Superheating fields of superconductors: Asymptotic analysis and numerical results

Starting from the assumption that the normal solid to supersolid (NS-SS) phase transition is continuous, we develop a phenomenological Landau theory of the transition in which superfluidity is coupled to the elasticity of the crystalline lattice. We find that the elasticity does not affect the universal properties of the superfluid transition, so that in an unstressed crystal the well-known anomaly in the heat capacity of the superfluid transition should also appear at the NS-SS transition. We also find that the onset of supersolidity leads to anomalies in the elastic moduli and thermal expansion coefficients near the transition and, conversely, that inhomogeneous lattice strains can induce local variations of the superfluid transition temperature, leading to a broadened transition.

Shapes of flux domains in the intermediate state of type-I superconductors

We derive the long-wavelength elastic theory for the quantum Hall smectic state starting from the Hartree-Fock approximation. Dislocations in this state lead to an effective nematic model for