Showing papers in "Physical Review Letters in 1971"
TL;DR: An exact solution for the Korteweg-de Vries equation for the case of multiple collisions of $N$ solitons with different amplitudes was obtained in this paper, which is the only known exact solution.
Abstract: An exact solution has been obtained for the Korteweg---de Vries equation for the case of multiple collisions of $N$ solitons with different amplitudes.
2,637 citations
TL;DR: In this paper, Fourier analysis was applied to the point-scattering theory of x-ray absorption fine structure to invert experimental data formally into a radial structure function with determinable structural parameters of distance from the absorbing atom, number of atoms, and widths of coordination shells.
Abstract: We have applied Fourier analysis to our point-scattering theory of x-ray absorption fine structure to invert experimental data formally into a radial structure function with determinable structural parameters of distance from the absorbing atom, number of atoms, and widths of coordination shells. The technique is illustrated with a comparison of evaporated and crystalline Ge. We find that the first and second neighbors in amorphous Ge are at the crystalline distance within the accuracy of measurement (1%).
1,180 citations
TL;DR: In this paper, it was shown that in a certain canonical sense, the Kerr metrics represent the exterior fields of black holes with the corresponding mass and angular-momentum values.
Abstract: A theorem is described which establishes the claim that in a certain canonical sense the Kerr metrics represent "the" (rather than merely "some possible") exterior fields of black holes with the corresponding mass and angular-momentum values.
1,131 citations
TL;DR: In this article, it was shown that there is an upper bound to the energy of the gravitational radiation emitted when one collapsed object captures another, in the case of two objects with equal masses and zero intrinsic angular momenta.
Abstract: It is shown that there is an upper bound to the energy of the gravitational radiation emitted when one collapsed object captures another. In the case of two objects with equal masses $m$ and zero intrinsic angular momenta, this upper bound is $(2\ensuremath{-}\sqrt{2})m$.
1,052 citations
TL;DR: In this article, it was shown that the spin configuration differs from the N\'eel type found in large crystallites, and it was proposed that the ions in the surface layer are inclined at various angles to the direction of the net moment.
Abstract: M\"ossbauer-effect measurements on extremely small (\ensuremath{\sim}60 \AA{}) crystallites of $\ensuremath{\gamma}\ensuremath{-}{\mathrm{Fe}}_{2}{\mathrm{O}}_{3}$ show that the spin configuration differs from the N\'eel type found in large crystallites. It is proposed that the ions in the surface layer are inclined at various angles to the direction of the net moment.
857 citations
TL;DR: In this paper, a self-consistent effective medium theory for resistor networks with all but a fraction $p$ of the resistors removed is studied, and the critical probability for bond percolation is analyzed.
Abstract: Electrical conduction in resistor networks with all but a fraction $p$ of the resistors removed is studied as a paradigm of classical transport in disordered materials. A self-consistent effective-medium theory provides a quantitative description of the model, except in a small critical region, where the scaling law ${\ensuremath{\sigma}}^{\ensuremath{\propto}}{(p\ensuremath{-}{p}_{c})}^{\frac{8}{5}}$ is satisfied (in three dimensions), with ${p}_{c}$ the critical probability for bond percolation. It is also contrasted with a critical-path analysis recently developed for the study of hopping conduction.
571 citations
TL;DR: The solution of the zero-field "eight-vertex" model is presented in this article, which includes the square lattice Ising, dimer, ice, $F, and KDP models as special cases.
Abstract: The solution of the zero-field "eight-vertex" model is presented. This model includes the square lattice Ising, dimer, ice, $F$, and KDP models as special cases. It is found that in general the free energy has a branch-point singularity at a phase transition, with a continuously variable exponent.
530 citations
TL;DR: In this article, the authors explain the spontaneous generation of magnetic fields in a laser-produced plasma using thermoelectric currents associated with large temperature gradients near the target, using a variety of targets and background pressures.
Abstract: Spontaneously generated magnetic fields of the order of a kilogauss have been observed in a laser-produced plasma, using a variety of targets and background pressures. The generation of these magnetic fields is explained in terms of thermoelectric currents associated with large temperature gradients near the target.
435 citations
TL;DR: In this paper, the spin-dependent tunneling density of superconducting aluminum and ferromagnetic nickel is determined by a polarization of the magnetic moments of the Ni current carriers parallel to the applied field.
Abstract: Tunneling measurements on junctions between very thin superconducting aluminum films and ferromagnetic nickel films in a high magnetic field show that the tunneling current is spin dependent. The effective tunneling density of states in Ni determined by this means implies a polarization of the magnetic moments of the Ni current carriers parallel to the applied field. The technique offers a new method for investigating spin-dependent states in magnetic materials.
399 citations
TL;DR: In this paper, it was shown that for every spacelike three-geometry there exists a symmetric tensor that is conformally invariant, traceless, and covariantly divergence free.
Abstract: It is shown that for every spacelike three-geometry there exists a symmetric tensor that is (1) defined locally using only the three-metric and its derivatives, (2) conformally invariant, (3) traceless, and (4) covariantly divergence free ("transverse"). As a result, the arbitrarily specifiable (unconstrained) initial-value data in the Einstein initial-value problem for gravity can be completely characterized by a pair of symmetric, transverse, traceless tensors.
399 citations
TL;DR: In this article, ideas from Griffin's exciton model are combined with those from the nucleon-nucleon scattering approach to nuclear transition times to provide a simple closed-form expression for predicting pre-equilibrium decay phenomena.
Abstract: Ideas from Griffin's exciton model are combined with those from the nucleon-nucleon scattering approach to nuclear transition times to provide a simple closed-form expression for predicting pre-equilibrium decay phenomena, including variation of pre-equilibrium emission with target mass, excitation energy, and initial particle and hole numbers. Time estimates for pre-equilibrium emission are given at several excitations.
TL;DR: In this paper, the large-order behavior of perturbation theory for the anharmonic oscillator was examined and the precise rate of divergence was derived for all energy levels of the oscillator.
Abstract: We examine the large-order behavior of perturbation theory for the anharmonic oscillator, a simple quantum-field-theory model. New analytical techniques are exhibited and used to derive formulas giving the precise rate of divergence of perturbation theory for all energy levels of the ${x}^{2N}$ oscillator. We compute higher-order corrections to these formulas for the ${x}^{4}$ oscillator with and without Wick ordering.
TL;DR: In this article, the bulk conductivity of a sheet of colloidal graphite paper with holes randomly punched in it was investigated and the behavior of the conductivity was found to be quite different from that of the percolation probability.
Abstract: We report the results of an experiment to determine the bulk conductivity of a sheet of colloidal graphite paper with holes randomly punched in it. The behavior of the conductivity is found to be quite different from that of the percolation probability.
TL;DR: In this article, the cross sections for quasielastic electron scattering from nine target nuclei from lithium to lead have been measured for an electron incident energy of 500 MeV and a scattering angle of 60.
Abstract: The cross sections for quasielastic electron scattering from nine target nuclei from lithium to lead have been measured for an electron incident energy of 500 MeV and a scattering angle of 60\ifmmode^\circ\else\textdegree\fi{}. The data are interpreted in terms of a Fermi gas model, yielding the nuclear Fermi momentum as a function of atomic number. The Fermi momentum increases from lithium to calcium and remains roughly constant at about 260 $\frac{\mathrm{MeV}}{c}$ from nickel to lead.
TL;DR: In this paper, the amorphous form of Si and several related, tetrahedrally bonded semiconductors (Ge, GaAs, GaP, InSb) were studied in the presence of Raman scattering.
Abstract: Raman scattering has been studied in the amorphous form of Si and several related, tetrahedrally bonded semiconductors (Ge, GaAs, GaP, InSb). All vibrational modes of the material can take part in the scattering process, and the Raman spectrum is a measure of the density of vibrational states. The amorphous phases are found to have vibrational spectra very similar to the corresponding crystals, reflecting the similarity in short-range order of the two phases.
TL;DR: In this paper, a theory of leptonic weak and electromagnetic interactions is proposed and the experimental implications of this theory and its extension to hadrons are briefly discussed, and the divergence difficulties present in conventional models are discussed.
Abstract: A previously proposed theory of leptonic weak and electromagnetic interactions is found to be free of the divergence difficulties present in conventional models. The experimental implications of this theory and its extension to hadrons are briefly discussed.
TL;DR: In this paper, a high-frequency test of Coulomb's law is described in terms of a finite photon rest mass using the Proca equations, and the sensitivity of the experiment is given in the form of the photon rest masses squared.
Abstract: A high-frequency test of Coulomb's law is described. The sensitivity of the experiment is given in terms of a finite photon rest mass using the Proca equations. The null result of our measurement expressed in the form of the photon rest mass squared is ${\ensuremath{\mu}}^{2}=(1.04\ifmmode\pm\else\textpm\fi{}1.2)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}19}$ ${\mathrm{cm}}^{\ensuremath{-}2}$. Expressed as a deviation from Coulomb's law of the form $\frac{1}{{r}^{2+q}}$, our experiment gives $q=(2.7\ifmmode\pm\else\textpm\fi{}3.1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}$. This result extends the validity of Coulomb's law by two orders of magnitude.
TL;DR: In this paper, the hyperfine splitting of the $D$ resonance lines has been studied in saturated absorption with a repetitively pulsed tunable dye laser, and a time-resolved observation of the collisional-velocity thermalization in the presence of Ar buffer gas is reported.
Abstract: The sodium $D$ resonance lines have been studied in saturated absorption with a repetitively pulsed tunable dye laser. The hyperfine splitting of the $3^{2}S_{\frac{1}{2}}$ and $3^{2}P_{\frac{1}{2}}$ states of ${\mathrm{Na}}^{23}$ is resolved. Measurements with a delayed probe reveal a remanent hole burning in the velocity distributions of the two ground-state levels, caused by a velocity-selective optical pumping cycle. A time-resolved observation of the collisional-velocity thermalization in the presence of Ar buffer gas is reported.
TL;DR: In this article, a selfconsistent treatment of the Kondo scattering of conduction electrons from magnetic impurities is presented in order to treat finite concentrations of such impurities in superconductors.
Abstract: A self-consistent treatment of the Kondo scattering of conduction electrons from magnetic impurities is presented in order to treat finite concentrations of such impurities in superconductors The present theory leads to a concentration dependence for the transition temperature which differs markedly from the Abrikosov-Gor'kov result The theory appears to account nicely for various experimental results We also find that superconductivity, under certain circumstances, does not exist at all temperatures below ${T}_{c}$
TL;DR: In this paper, the thermodynamics of the Heisenberg-ising ring is reduced to the solution of a system of recurrent nonlinear integral equations, which is the same as our solution.
Abstract: The thermodynamics of the Heisenberg-Ising ring is reduced to the solution of a system of recurrent nonlinear integral equations.
IBM1
TL;DR: In this article, the rotational displacement parameters below the second-order phase transitions in SrTi${\mathrm{O}}_{3}$ and LaAl${O}$ at T{T}_{a}=105.5
Abstract: The temperature dependence of the rotational displacement parameters below the second-order phase transitions in SrTi${\mathrm{O}}_{3}$ and LaAl${\mathrm{O}}_{3}$ at ${T}_{a}=105.5 \mathrm{and} 797$\ifmmode^\circ\else\textdegree\fi{}K is described by an exponent $\ensuremath{\beta}=0.33\ifmmode\pm\else\textpm\fi{}0.02$ down to $t=\frac{T}{{T}_{a}}=0.95$. For smaller $t$'s there occurs a change to Landau behavior approximately followed between $t=0.9 \mathrm{and} 0.7$. The observation of static critical exponents near displacive phase transitions confirms now the notion of universality in this field.
IBM1
TL;DR: Theoretical computations of the nutation effect agree with observation, and echo characteristics closely follow predictions of existing theories as mentioned in this paper, and it is shown that echo relaxes primarily by rotational energy transfer.
Abstract: Photon echo and optical nutation have been easily observed in ${\mathrm{C}}^{13}$${\mathrm{H}}_{3}$F and N${\mathrm{H}}_{2}$D by applying Stark pulses which shift the molecular levels into resonance with cw laser radiation. Numerical computations of the nutation effect agree with observation, and echo characteristics closely follow predictions of existing theories. The $T_{2}^{}{}_{}{}^{\ensuremath{'}}$ pressure dependence, from infrared-echo measurements, indicates that ${\mathrm{C}}^{13}$${\mathrm{H}}_{3}$F relaxes primarily by rotational energy transfer.
TL;DR: In this paper, the temperature dependence of the dielectric constants for single-domain SrTi${\mathrm{O}}_{3}$ crystals was measured and deviations from the simple Curie-Weiss law were discussed in connection with the structural phase transitions at 110 and 65 degrees.
Abstract: We have measured the temperature dependence of the dielectric constants for single-domain SrTi${\mathrm{O}}_{3}$ crystals. Dielectric anisotropies and deviations from the simple Curie-Weiss law have been observed and are discussed in connection with the structural phase transitions at 110 and 65\ifmmode^\circ\else\textdegree\fi{}K.
TL;DR: The ground state of the $4f$ shell in the metallic high-pressure collapsed phase is nonmagnetic, contrary to Hund's rules as discussed by the authors, which is correlated with an intermediate valence in SmS, Sm${\mathrm{B}}_{6}$, and
Abstract: The magnetic susceptibility of SmS indicates a discontinuous and hysteretic magnetic transition at 6 kbar. The ground state of the $4f$ shell in the metallic high-pressure "collapsed" phase is nonmagnetic, contrary to Hund's rules. Nonmagnetic behavior of the $4f$ shell is correlated with an intermediate valence in SmS, Sm${\mathrm{B}}_{6}$, and $\ensuremath{\alpha}\ensuremath{-}\mathrm{Ce}$. It is suggested that in such intermediate-valence phases at $T=0$ the $4f$ shell is demagnetized in the sense of the Friedel-Anderson model as modified by Hirst.
TL;DR: In this article, the authors show that the widely accepted simple "proton model" of Pd/H is misleading, and also explain why the added number of electrons (0.6) in $\ensuremath{\beta}$-phase PdH exceeds the number of $d$-band holes in Pd.
Abstract: Photoemission studies of the Pd/H system show a band of hydrogen-induced energy states centered at 1 eV below the bottom of Pd-derived d bands of width 4.4 eV. These results show that the widely accepted simple "proton model" of Pd/H is misleading. Our augmented-plane-wave calculations of PdH, ${\mathrm{Pd}}_{4}$${\mathrm{H}}_{3}$, and ${\mathrm{Pd}}_{4}$H exhibit these lowlying states and also explain why the added number of electrons (0.6) in $\ensuremath{\beta}$-phase PdH exceeds the number of $d$-band holes (0.36) in Pd.
TL;DR: In this article, a more stringent test of the predicted relativistic increase in echo times of radio signals sent from Earth and reflected from Mercury and Venus is presented, which is characterized by a parameter $\ensuremath{\lambda}$ which is unity according to general relativity and 0.93 according to recent predictions based on a scalar-tensor theory of gravitation.
Abstract: New radar observations yield a more stringent test of the predicted relativistic increase in echo times of radio signals sent from Earth and reflected from Mercury and Venus. These "extra" delays may be characterized by a parameter $\ensuremath{\lambda}$ which is unity according to general relativity and 0.93 according to recent predictions based on a scalar-tensor theory of gravitation. We find that $\ensuremath{\lambda}=1.02$. The formal standard error is 0.02, but because of the possible presence of systematic errors we consider 0.05 to be a more reliable estimate of the uncertainty in the result.
TL;DR: Magnetic relaxation in one-dimensional exchange-coupled paramagnets is found to be dramatically different than it is in three dimensional exchange-narrowed ones as discussed by the authors, and a theory which accounts properly for the special long-time persistence of spin correlation functions in one dimension is shown to explain the observed behavior.
Abstract: Magnetic relaxation in one-dimensional exchange-coupled ${(\mathrm{C}{\mathrm{H}}_{3})}_{4}$NMn${\mathrm{Cl}}_{3}$ is found to be dramatically different than it is in three-dimensional exchange-narrowed paramagnets. A theory which accounts properly for the special long-time persistence of spin-correlation functions in one dimension is shown to explain the observed behavior.