Showing papers by "Yoseph Imry published in 1980"
TL;DR: The limit of a small first-order transition is shown to be consistent with a second-order one in this paper, which is relevant both for real and computer experiments on systems that are quite small but larger than microscopic sizes.
Abstract: The finite-size broadening of a first-order phase transition is estimated to be proportional to the inverse of the product of the system size and the latent entropy of the transition. The relation to the usual second-order-transition case is discussed. The limit of a small first-order transition is shown to be consistent with a second-order one. These results are relevant both for real and computer experiments on systems that are quite small but larger than microscopic sizes.
144 citations
TL;DR: The scaling theory of Anderson localization by Abrahams et al. as discussed by the authors is used for dirty conductors just above the Anderson transition, where the inelastic mean free path is smaller than the coherence length, in the extended phase, the conductivity increases with temperature like
Abstract: The scaling theory of Anderson localization by Abrahams et al. is used for dirty conductors just above the Anderson transition. When the inelastic mean free path, ${l}_{\mathrm{ph}}$, is smaller than the coherence length, $\ensuremath{\xi}$, in the extended phase, the conductivity increases with temperature like ${{l}_{\mathrm{ph}}}^{\ensuremath{-}1}$. This may be related to the quite general correlation between large resistances and their negative temperature derivatives found by Mooij. ${l}_{\mathrm{ph}}g\ensuremath{\xi}$ is required to distinguish between the extended and localized regimes.
136 citations
TL;DR: In this paper, time-periodic solutions for the Josephson phase equation for a finite-length tunnel junction with uniform current feed and linear loss term were found and exact currentvoltage characteristics were compared with simple approximations.
47 citations
TL;DR: In this paper, a scaling property of the structure factor is derived as a function of the momentum transfer components parallel and perpendicular to the smectic layers of a 2D liquid crystal.
Abstract: The two-dimensional ($2D$) crystal and the $3D$ smectic-$A$ liquid crystal are examples of Landau-Peierls systems, where long-wavelength fluctuations wash out long-range order of the order parameter. However, the decay of the order-parameter correlation functions is of the power-law type, rather than exponential. The result is that in x-ray scattering characteristic power-law singularities appear instead of the usual Bragg peaks. The details of these singularities, which have recently been observed experimentally in a smectic-$A$ liquid crystal by Als-Nielsen et al., are analyzed for the smectic-$A$ case. A new scaling property of the structure factor is derived as a function of the momentum-transfer components parallel ($\ensuremath{\kappa}$) and perpendicular (${K}_{\ensuremath{\perp}}$) to the smectic layers. Very close to the Bragg points, finite-size effects become important, including a new and unusual effect when ${K}_{\ensuremath{\perp}}$ is proportional to the inverse square root of the finite thickness of the specimen. The crossover in the Bragg peaks due to order-restoring effects of an external magnetic field is presented.
41 citations
TL;DR: In this paper, it was shown that for temperatures so low that k/sub B/T is much less than the rest energy of a soliton, the mean square displacement of a diffusing particle of an infinite sine-Gordon chain behaves as t/sup 1/2/ for times much longer than microscopic times but much shorter than the soliton lifetime tau.
Abstract: Theoretical evidence is presented that for temperatures so low that k/sub B/T is much less than the rest energy of a soliton, the mean square displacement of a diffusing particle of an infinite sine-Gordon chain behaves as t/sup 1/2/ for times much longer than microscopic times but much shorter than the soliton lifetime tau. For times much greater than tau, linear behavior is suggested. Finite-size effects are discussed in the context of recent computer simulation studies.
22 citations
TL;DR: In this paper, the dynamics of a small Josephson junction, driven either by a current source or by an external flux when the junction is the weak link element of a SQUID ring, were studied.
Abstract: The dynamics of a small Josephson junction, driven either by a current source or by an external flux when the junction is the weak link element of a SQUID ring, were studied. Approximate analytical arguments and numerical simulations were used for the lumped circuit model of the junction. The various characteristic times of these devices were systematically obtained as functions of the parameters G and K of the junction and of the SQUID, respectively. The forms of the flux transitions and the times governing them are obtained for linear and periodic time variations of the external flux on the SQUID. A coupling of the SQUID to an LC circuit was treated. Limitations on the device parameters consistent with fast response, stability, and sensitivity were obtained both for the current driven junction and for the rf SQUID.
13 citations
TL;DR: In this article, the first-order solid-fluid transition is reviewed and the possibility of the transition becoming second-order due to fluctuations is discussed qualitatively, depending on the relative sizes of the firstorder transition and the critical region of the fluctuations.
Abstract: Crystalline order parameters related to the localization of the particles within the cells are introduced into the usual lattice-gas model. The coupling of these order parameters to the usual liquid-gas transition is shown to produce, in the simplest approximation, phase diagrams of qualitatively correct shapes. The Goldstone modes of the solid are retained in this picture. The Landau theory of melting is reviewed and shown to always lead to a first-order solid-fluid transition. The question of the possibility of the transition becoming second order due to fluctuations is discussed qualitatively. This possibility is shown to depend on the relative sizes of the first-order transition and the critical region of the fluctuations.
4 citations
01 Jan 1980
TL;DR: In this article, the scaling behavior of universal current scaling in the critical region above a 2D superconducting transition in a granular NbN film suggests that a phase transition occurs at finite temperature and critical exponents and constants are determined.
Abstract: Publisher Summary The reporting of universal current scaling in the critical region above a 2D superconducting transition in a granular NbN film suggests that a phase transition occurs at finite temperature and critical exponents and constants are determined. Using these exponents and constants, the universal scaling behavior is shown to extend below finite temperature. The form of the scaling function in the low temperature regime predicts a temperature dependence of the critical current in the critical region that agrees remarkably well with the experimental values for finite temperature. Critical currents are also measured in the temperature regime below the critical region. The chapter explains how the exponents and constants are determined above a finite temperature. The extrapolated intercept of the scaling function predicts the temperature dependence of critical currents in the critical region. A sharp rise in the critical current at a characteristic temperature may be associated with another transition in the samples.