Showing papers in "Physical Review Letters in 1989"
TL;DR: In this article, the authors present a method for optimizing the analysis of data from multiple Monte Carlo computer simulations over wide ranges of parameter values, which is applicable to simulations in lattice gauge theories, chemistry, and biology, as well as statistical mechanics.
Abstract: We present a new method for optimizing the analysis of data from multiple Monte Carlo computer simulations over wide ranges of parameter values. Explicit error estimates allow objective planning of the lengths of runs and the parameter values to be simulated. The method is applicable to simulations in lattice gauge theories, chemistry, and biology, as well as statistical mechanics.
2,198 citations
TL;DR: A Monte Carlo algorithm is presented that updates large clusters of spins simultaneously in systems at and near criticality and its efficiency is demonstrated in the two-dimensional $\mathrm{O}(n)$ $\ensuremath{\sigma}$ models.
Abstract: A Monte Carlo algorithm is presented that updates large clusters of spins simultaneously in systems at and near criticality. We demonstrate its efficiency in the two-dimensional $\mathrm{O}(n)$ $\ensuremath{\sigma}$ models for $n=1$ (Ising) and $n=2$ ($x\ensuremath{-}y$) at their critical temperatures, and for $n=3$ (Heisenberg) with correlation lengths around 10 and 20. On lattices up to ${128}^{2}$ no sign of critical slowing down is visible with autocorrelation times of 1-2 steps per spin for estimators of long-range quantities.
1,965 citations
TL;DR: It is proposed that the fractional quantum Hall effect of electrons can be physically understood as a manifestation of the integer quantumHall effect of composite fermionic objects consisting of electrons bound to an even number of flux quanta.
Abstract: In the standard hierarchical scheme the daughter state at each step results from the fractional quantum Hall effect of the quasiparticles of the parent state. In this paper a new possible approach for understanding the fractional quantum Hall effect is presented. It is proposed that the fractional quantum Hall effect of electrons can be physically understood as a manifestation of the integer quantum Hall effect of composite fermionic objects consisting of electrons bound to an even number of flux quanta.
1,625 citations
TL;DR: In this paper, a new approach to correlated Fermi systems such as the Hubbard model, the periodic Anderson model etc. is discussed, which makes use of the limit of high spatial dimensions.
Abstract: A new approach to correlated Fermi systems such as the Hubbard model, the periodic Anderson model etc. is discussed, which makes use of the limit of high spatial dimensions. This limit — which is wellknown in the case of classical as well as localized quantum spin models — is found to be very helpful also in the case of quantum mechanical models with itinerant degrees of freedom. Many investigations, which are prohibitively difficult in lower dimensions, become tractable in this limit. In particular, essential features of systems in d = 3, and even lower dimensions, are very well described by the results in d = ∞ or expansions around this limit. A brief review of the state-of-the-art is presented.
1,605 citations
TL;DR: The generalization given here yields, with ∣B∣ ≠ ∣A∣, the first provable example of itinerant electron ferromagnetism, and the theorems hold in all dimensions without even the necessity of a periodic lattice structure.
Abstract: In the attractive Hubbard model (and some extended versions of it) the ground state is proved to have spin angular momentum S = 0 for every (even) electron filling. In the repulsive case, and with a bipartite lattice and a half filled band, the ground state has S = 1/2∥B∣ − ∣A∥, where ∣B∣ (resp. ∣A∣) is the number of sites in the B (resp. A) sublattice. In both cases the ground state is unique. These theorems hold for all values of U, the attraction or repulsion parameter. The second theorem confirms an old, unproved conjecture in the ∣B∣ = ∣A∣ case; the generalization given here yields, with ∣B∣ ≠ ∣A∣, the first provable example of itinerant electron ferromagnetism. Since topology is irrelevant for the proofs, the theorems hold in all dimensions without even the necessity of a periodic lattice structure.
1,575 citations
TL;DR: The universal anomalies in the normal state of Cu-O high-temperature superconductors follow from a single hypothesis: There exist charge- and spin-density excitations with the absorptive part of the polarizability at low frequencies proportional to T, where T is the temperature, and constant otherwise.
Abstract: The universal anomalies in the normal state of Cu-O high-temperature superconductors follow from a single hypothesis: There exist charge- and spin-density excitations with the absorptive part of the polarizability at low frequencies \ensuremath{\omega} proportional to \ensuremath{\omega}/T, where T is the temperature, and constant otherwise. The behavior in such a situation may be characterized as that of a marginal Fermi liquid. The consequences of this hypothesis are worked out for a variety of physical properties including superconductivity.
1,399 citations
TL;DR: A free-energy density functional for the inhomogeneous hard-sphere fluid mixture is derived from general basic considerations and yields explicit analytic expressions for the high-order direct correlation functions of the uniform fluid.
Abstract: A free-energy density functional for the inhomogeneous hard-sphere fluid mixture is derived from general basic considerations and yields explicit analytic expressions for the high-order direct correlation functions of the uniform fluid. It provides the first unified derivation of the most comprehensive available analytic description of the hard-sphere thermodynamics and pair structure as given by the scaled-particle and Percus-Yevick theories. The infinite-order expansion around a uniform reference state does not lead, however, to a stable solid, thus questioning the convergence of the density-functional theory of freezing.
1,389 citations
TL;DR: In this paper, a nonzero Berry phase is shown to exist in a one-dimensional parameter space and a connection between the latter and the Wyckoff positions in the crystal in the framework of band representations of space groups is established.
Abstract: Berry's phase is defined for the dynamics of electrons in periodic solids and an explicit formula is derived for it. Because of the special torus topology of the Brillouin zone a nonzero Berry phase is shown to exist in a one-dimensional parameter space. Symmetry of the Bloch functions in the Brillouin zone leads to the quantization of Berry's phase. A connection is established between the latter and the Wyckoff positions in the crystal in the framework of band representations of space groups. Berry's phase can therefore be used for labeling energy bands in solids.
1,386 citations
IBM1
TL;DR: In this article, the optical absorption spectrum of single dopant molecules of pentacene in a p-terphenyl host crystal at liquid-helium temperatures was observed using two different double-modulation techniques.
Abstract: Using two different double-modulation techniques, we have observed the optical-absorption spectrum of single dopant molecules of pentacene in a p-terphenyl host crystal at liquid-helium temperatures. To achieve this, frequency-modulation spectroscopy was combined either with Stark or ultrasonic modulation to remove interfering background signals from residual amplitude modulation, and the number of molecules in resonance was reduced to one by operating in the wings of the inhomogeneous line. Triplet bottleneck saturation appears to be suppressed in the single-molecule regime.
1,108 citations
IBM1
TL;DR: The possibility of a new thermodynamic phase in the mixed state of bulk, disordered, type-II superconductors is suggested: a vortex-glass superconductor that lacks conventional off-diagonal long-ranged order, yet is argued to be a true super Conductor with vanishing dc resistance.
Abstract: The possibility of a new thermodynamic phase in the mixed state of bulk, disordered, type-II superconductors is suggested: a vortex-glass superconductor. This phase lacks conventional off-diagonal long-ranged order, yet is argued to be a true superconductor with vanishing dc resistance. In this phase metastable currents are predicted to decay as (lnt${)}^{\mathrm{\ensuremath{-}}1/\mathrm{\ensuremath{\mu}}}$ with \ensuremath{\mu}(\ensuremath{\le}1) a universal exponent. Relevance to experiments on bulk high-${\mathrm{T}}_{\mathrm{c}}$ oxides is mentioned.
1,019 citations
TL;DR: A technique is presented that directly reconstructs minimal equations of motion from the recursive structure of measurement sequences, demonstrating a form of superuniversality that refers only to the entropy and complexity of a data stream.
Abstract: Statistical mechanics is used to describe the observed information processing complexity of nonlinear dynamical systems. We introduce a measure of complexity distinct from and dual to the information theoretic entropies and dimensions. A technique is presented that directly reconstructs minimal equations of motion from the recursive structure of measurement sequences. Application to the period-doubling cascade demonstrates a form of superuniversality that refers only to the entropy and complexity of a data stream.
IBM1
TL;DR: The nature of Mn impurity is discussed, and experimental pieces of evidence suggesting the dominating role of Mn (d5 ) configuration are given, together with resulting magnetooptical properties and some selected problems of quantum structures based on III—V diluted magnetic semiconductors are discussed.
Abstract: A new diluted magnetic III-V semiconductor of ${\mathrm{In}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${\mathrm{Mn}}_{\mathrm{x}}$As (x\ensuremath{\le}0.18) has been produced by molecular-beam epitaxy. Films grown at 300 \ifmmode^\circ\else\textdegree\fi{}C are predominantly ferromagnetic and their properties suggest the presence of MnAs clusters. Films grown 200 \ifmmode^\circ\else\textdegree\fi{}C, however, are predominantly paramagnetic, and the lattice constant decreases with increasing Mn composition; both are indicative of the formation of a homogeneous alloy. These films have n-type conductivity and reduced band gaps.
TL;DR: The muon-spin-relaxation rate sigma has been measured in sixteen specimens of high-T/ sub c/ cuprate superconductors and a universal linear relation between T/sub c/ and sigma(T..-->..0)proportionaln/sub s//m/sup */ has been found with increasing carrier doping.
Abstract: The muon-spin-relaxation rate sigma has been measured in sixteen specimens of high-T/sub c/ cuprate superconductors (the 2:1:4, 1:2:3, 2:2:1:2, and 2:2:2:3 series). This has allowed us to study the magnetic field penetration depth lambda and thus the superconducting carrier density n/sub s/ divided by the effective mass m/sup */ (sigmaproportional1/lambda/sup 2/proportionaln/sub s//m/sup */). A universal linear relation between T/sub c/ and sigma(T..-->..0)proportionaln/sub s//m/sup */ has been found with increasing carrier doping. In heavily doped samples, however, T/sub c/ shows saturation and suppression with increasing n/sub s//m/sup */. This saturation starts at different values of n/sub s//m/sup */ for materials with different multiplicities of CuO planes.
TL;DR: The quantum-mechanical uncertainty in the position of a particle or the time of its emission is shown to produce observable effects that are inconsistent with any local hidden-variable theory.
Abstract: The quantum-mechanical uncertainty in the position of a particle or the time of its emission is shown to produce observable effects that are inconsistent with any local hidden-variable theory. A new experimental test of local hidden-variable theories based on optical interference is proposed.
IBM1
TL;DR: In this article, the role of surface active species (surfactants) in heteroepitaxial growth was investigated and the use of a segregating surfactant was proposed to reduce the surface free energies of A and B and suppress island formation, as demonstrated in the growth of Si/Ge/Si(001) with a monolayer of As.
Abstract: We have investigated the role of surface-active species (surfactants) in heteroepitaxial growth. In general, the growth mode is determined by the balance between surface, interface, and film free energies. Thus, if A wets B, B will not wet A. Any attempt at growing an A/B/A heterostructure must overcome this fundamental obstacle. We propose the use of a segregating surfactant to reduce the surface free energies of A and B and suppress island formation, as demonstrated in the growth of Si/Ge/Si(001) with a monolayer of As. Control of growth by amnipulation of surface energetics provides a new avenue to achieve high-quality man-made microstructures against thermodynamic odds.
TL;DR: In this article, a simple method for computing f(ensuremath{\alpha}) based on the theorems of Shannon, Eggelston, and Billingsley is presented. But this method is not suitable for low-dimensional chaotic systems where the underlying dynamics are unknown.
Abstract: The direct determination of the f(\ensuremath{\alpha}) singularity spectrum from experimental data is a difficult problem. This Letter introduces a simple method for computing f(\ensuremath{\alpha}) based on the theorems of Shannon, Eggelston, and Billingsley which is markedly superior to other recently proposed methods, especially when dealing with experimental data from low-dimensional chaotic systems where the underlying dynamics are unknown.
TL;DR: The statistical mechanics of a simple lattice model for the denaturation of the DNA double helix are investigated and it is shown that amechanism involving an energy localization analogous to self-focusing mayinitiate the Denaturation.
Abstract: We investigate the statistical mechanics of a simple lattice model for the denaturation of the DNA double helix. The model consists of two chains connected by Morse potentials representing the H bonds. We determine the temperature dependence of the interstrand separation and we show that a mechanism involving an energy localization analogous to self-focusing may initiate the denaturation.
TL;DR: The nature of flux-creep phenomena in the case of collective pinning by weak disorder is discussed and the Anderson concept of flux bundle is explored and developed.
Abstract: The nature of flux-creep phenomena in the case of collective pinning by weak disorder is discussed. The Anderson concept of flux bundle is explored and developed. The dependence of the bundle activation barrier U on current j is studied and is shown to be of power-law type: U(j) is proportional to j exp -alpha. The values of exponent alpha for the different regimes of collective creep are found.
TL;DR: A single lasing mode driven by a three-level ''quantum-beat'' atomic configuration can show gain without population inversion or optical absorption into an excited state without spontaneous or stimulated emission.
Abstract: A single lasing mode driven by a three-level ``quantum-beat'' atomic configuration can show gain without population inversion or optical absorption into an excited state without spontaneous or stimulated emission.
TL;DR: It is discovered that the Ce4+doping and subsequent annealing in reducing atmosphere give rise to 24-K superconductivity in the Nd2CuO4-type structure with sheets of Cu-O squares, in contrast to the previously reported high-Tccuprates.
Abstract: We have discovered that the Ce4+doping and subsequent annealing in reducing atmosphere give rise to 24-K superconductivity in the Nd2CuO4-type structure with sheets of Cu-O squares. In contrast to the previously reported high-Tccuprates, the charge carriers in the new superconductors are doped electrons, not holes; this was confirmed by the measurements of Hall and Seebeck coefficients as well as by chemical analysis of the effective copper valence. An anomalous dependence ofTcon the concentration of doped electrons is shown for these electron-doped superconducting cuprates.
TL;DR: The monopole exerts practically no gravitational force on nonrelativistic matter, but the space around it has a deficit solid angle, and all light rays are deflected by the same angle, independent of the impact parameter.
Abstract: We present an approximate solution of the Einstein equations for the metric outside a monopole resulting from the breaking of a global O(3) symmetry. The monopole exerts practically no gravitational force on nonrelativistic matter, but the space around it has a deficit solid angle, and all light rays are deflected by the same angle, independent of the impact parameter.
TL;DR: It is shown that the poloidal momentum balance equation in tokamaks has bifurcated solutions and the theory is employed to explain the {ital L-{ital H} transition observed in toKamaks.
Abstract: It is shown that the poloidal momentum balance equation in tokamaks has bifurcated solutions. The poloidal flow velocity ${U}_{p}$ can suddenly become more positive when the ion collisionality decreases. The corresponding radial electric field ${E}_{r}$ becomes more negative and hence suppresses the turbulent fluctuations. Thus, plasma confinement is improved. The theory is employed to explain the L-H transition observed in tokamaks.
TL;DR: Description theorique simple des effets de magnetoresistance geante mesures recemment dans les structures Fe/Cr en couches dans la diffusion des electrons suivant la direction de leur spin.
Abstract: We present a simple theoretical description of recently measured giant magnetoresistance effects in Fe/Cr layered structures. The resistivity is calculated by solving the Boltzmann transport equation with spin-dependent scattering at the interfaces. The magnitude of the effect depends on the ratio of the layer thickness to the mean free path and on the asymmetry in scattering for spin-up and spin-down electrons. Good agreement with experiment is found for both sandwich structures and superlattices.
TL;DR: A field-theory model for the fractional quantum Hall effect and an approximate coarse-grained version of the same model are derived, and a Landau-Ginzburg theory similar to that of Girvin is constructed.
Abstract: Starting directly from the microscopic Hamiltonian, a field-theory model is derived for the fractional quantum Hall effect. By considering an approximate coarse-grained version of the same model, a Landau-Ginzburg theory similar to that of Girvin (1986) is constructed. The partition function of the model exhibits cusps as a function of density. It is shown that the collective density fluctuations are massive.
TL;DR: A new type of inflationary scenario based on metric formulations of gravity different from that of Einstein, e.g., Brans-Dicke theory of gravity is presented, which can be completed via bubble nucleation and fine tuning of an effective potential to obtain a slow-rollover transition.
Abstract: We present a new type of inflationary scenario based on metric formulations of gravity different from that of Einstein, e.g., a Brans-Dicke theory of gravity. Unlike previous inflation models, the inflationary phase transition can be completed via bubble nucleation. Hence, the fine tuning of an effective potential to obtain a slow-rollover transition is not required.
TL;DR: A single trapped 198 Hg + ion was cooled by scattering laser radiation that was tuned to the resolved lower motional sideband of the narrow 2 S 1/2 - 2 D 5/2 transition to indicate that the ion was in the ground state of its confining well approximately 95% of the time.
Abstract: A single trapped $^{198}\mathrm{Hg}^{+}$ ion was cooled by scattering laser radiation that was tuned to the resolved lower motional sideband of the narrow $^{2}S_{\frac{1}{2}}\ensuremath{-}^{2}D_{\frac{5}{2}}$ transition. The different absorption strengths on the upper and lower sidebands after cooling indicated that the ion was in the ground state of its confining well approximately 95% of the time.
IBM1
TL;DR: It is demonstrated experimentally the existence of a continuous phase transition between a normal and a true superconducting phase (with zero linear resistivity) in epitaxial films of Y-Ba-Cu-O in strong magnetic fields fields.
Abstract: We demonstrate experimentally the existence of a continuous phase transition between a normal and a true superconducting phase (with zero linear resistivity) in epitaxial films of Y-Ba-Cu-O in strong magnetic fields fields, {ital H}{much gt}{ital H}{sub {ital c}1}. The nonlinear {ital I}-{ital V} curves show scaling behavior near the transition and the relevant critical exponents are extracted. These exponents are consistent with values expected for freezing into a superconducting vortex-glass phase.
TL;DR: This work has identified one particular dielectric ``crystal'' which actually has a ``photonic band gap'' and requires a refractive index contrast greater than 3 to 1, which happens to be readily obtainable in semiconductor materials.
Abstract: We employ the concepts of band theory to describe the behavior of electromagnetic waves in three dimensionally periodic face-centered-cubic (fcc) dielectric structures. This can produce a ``photonic band gap'' in which optical modes, spontaneous emission, and zero-point fluctuations are all absent. In the course of a broad experimental survey, we have found that most fcc dielectric structures have ``semimetallic'' band structure. Nevertheless, we have identified one particular dielectric ``crystal'' which actually has a ``photonic band gap.'' This dielectric structure, consisting of 86% empty space, requires a refractive index contrast greater than 3 to 1, which happens to be readily obtainable in semiconductor materials.
TL;DR: It is pointed out that local symmetry invariance can masquerade as discrete global symmetries to an observer equipped with only low-energy probes, and black holes can carry discrete gauge charges, a form of nonclassical ``hair.
Abstract: We point out that local symmetries can masquerade as discrete global symmetries to an observer equipped with only low-energy probes. The existence of the underlying local gauge invariance can, however, result in observable Aharonov-Bohm-type effects. Black holes can therefore carry discrete gauge charges---a form of nonclassical ``hair.'' Neither black-hole evaporation, wormholes, nor anything else can violate discrete gauge symmetries. In supersymmetric unified theories such discrete symmetries can forbid proton-decay amplitudes that might otherwise be catastrophic.
TL;DR: A new technique is described for investigating phase transitions and dynamics in interacting electron systems based on the derivation and self-consistent solution of infinite-order conserving approximations that provides a new approach to the study of two-particle correlations with strong frequency and momentum dependence.
Abstract: A semianalytical approach is described for strongly correlated electronic systems which satisfies microscopic conservation laws, treats strong frequency and momentum dependences, and provides information on both static and dynamic properties. This approach may be used to treat large systems and temperatures lower than those currently accessible to finite-temperature quantum Monte Carlo techniques. Examples of such systems include heavy-electron compounds, organic Bechegaard salts, bis-(ethylenedithiolo)-TTF superconductors, and the oxide superconductors. The technique is based on the derivation and self-consistent solution of infinite-order conserving approximations. The technique is used to derive a low-temperature phase diagram and dynamic correlation functions for the two-dimensional Hubbard lattice model.