We report the studies of the elasticity of ${\mathrm{O}}_{60}$ single crystals. For sublimed fcc crystals, Young’s modulus has an 8% jump at the first-order transition at 260 K. At ∼160 K there is a frequency-dependent elastic anomaly resulting from time dependent stress relaxation. Comparison with rotation rates seen in NMR suggests that the dynamics below 260 K is more complex than jumps between equivalent molecular configurations. Solvent grown monoclinic crystals have a second-order transition at 242 K, while the 160-K glass transition remains unchanged.

The line shape of the Al 2p core-level photoemission peak in ${\mathrm{Al}}_{0.9}$${\mathrm{Ga}}_{0.1}$As is found to be strongly dependent on the electron kinetic energy. Using Monte Carlo transport simulations it is shown that the observed strong, asymmetric line broadening is caused by electron-phonon scattering. In agreement with the experimental observation, the simulations predict that this phonon-induced line broadening is rapidly suppressed as the core line is shifted through the impact-ionization threshold. Thus, it becomes possible to infer from the core-level line shape the energy-dependent impact-ionization rates near the impact-ionization threshold.

Using synchrotron radiation we measured the x-ray absorption (XAS) near the ${\mathrm{C}}_{1\mathit{s}}$ edge for powdered graphite, boron substituted graphite, and a disordered graphitic carbon. The chemical potential of Li intercalated into the same carbons has also been measured as a function of x in ${\mathrm{Li}}_{\mathit{x}}$${\mathrm{C}}_6$. When Li is intercalated, the 2s electron is transferred to the C host, filling the same levels as probed by XAS. In XAS, final-state energies contain a contribution from the electron–core-hole interaction which mimics the situation in Li intercalation where ${\mathrm{Li}}^{+}$ interacts with conduction electrons. We show that XAS results correlate well with chemical potential measurements of intercalated Li made on the same materials.

Uniaxial anisotropy has been found in ultrathin cobalt films grown on a Cu(1 1 13) surface. Our studies using scanning electron microscopy with polarization analysis clearly show that the easy axis of magnetization is parallel to the direction of the step edges of the Cu(1 1 13) substrate. In spite of the different anisotropy behavior, the domain structures in Co/Cu(001) and Co/Cu(1 1 13) are similar, which indicates that the domain pattern in ultrathin films is little affected by the anisotropy.

A two-particle state can be sensitive to a magnetic flux through exchange even if it is composed of single-particle states which on the average are statistically uncorrelated and exhibit no direct interference. Consequently, two-particle observables can be sensitive to a flux even if all single-particle observables are flux insensitive. We investigate exchange effects in current cross correlations of small conductors subject to a magnetic field.

The diffuseness of the ferroelectric phase transition in ${\mathrm{PbMg}}_{1/3}$${\mathrm{Nb}}_{2/3}$${\mathrm{O}}_3$ is proposed to be due to quenched random electric fields originating from charged compositional fluctuations. They are responsible for the extreme critical slowing down, the freezing into nanometric ferroelectric domains, and the slow relaxation of the polarization below ${\mathit{T}}_{\mathit{c}}$∼212 K. Barkhausen jumps during poling exclude glassiness, which was conjectured previously. At ${\mathit{T}}_{\mathit{c}}$ a ferroelectric anomaly of the dielectric permittivity appears, if the random fields are overcome by an external electric field.

Ferromagnetism of 5d transition metal monolayers is predicted for the first time. For Ir on Ag and Au(001) magnetic moments of 0.9${\mathrm{\mu }}_{\mathit{B}}$ were found by ab initio alculations based on the full-potential linearized augmented-plane-wave method. Os is magnetic on Ag but nonmagnetic on Au. Comparing 5d magnetism with 4d and 3d results, a remarkable trend emerges: The element with the largest moment among the 3d, 4d, and 5d monolayers is shifted from Mn to Ru (isoelectronic to Fe) and to Ir (isoelectronic to Co), respectively. 4d and 5d magnetism is explained as a true-dimensional band-structure effect.

We show that the classical Heisenberg antiferromagnet on a Kagomé lattice is an example of a spin nematic. By calculating the effects of thermal fluctuations around ground states, and by Monte Carlo simulations, we find entropically driven, local spin-nematic order at low temperature T with a correlation length which is divergent in the limit T→0. Dynamical correlations are also studied, within the harmonic approximation, in the nematically ordered states.

We have performed detailed studies of the structure, magnetotransport, and magnetization of Fe/Cr superlattices as a function of systematic changes in interfacial roughness. The results clearly show that the giant magnetoresistance is enhanced by the presence of roughness. This fact indicates that interfacial roughness should be explicitly included in theoretical calculations and experimental characterization of superlattices exhibiting giant magnetoresistance.

We demonstrate an anomalous x-ray-diffraction procedure for the determination of pair correlations in crystalline solid solutions. This procedure experimentally removes the large thermal diffuse scattering background with no assumptions and permits separation of chemically specific static displacements. We recover the near-neighbor chemical order and static displacements in a ${\mathrm{Fe}}_{22.5}$${\mathrm{Ni}}_{77.5}$ single crystal quenched from 1000 °C. The Fe-Fe nearest-neighbor distance is dilated by ∼0.043 Å from the average lattice. The possible magnetic origins of this dilation are discussed.

The induced magnetization of an isotropic type-II superconductor with an anisotropic sample shape has been measured in an oblique magnetic field and separated into its reversible and irreversible contributions. The measurements unexpectedly show that the irreversible magnetization is oriented essentially parallel to the smallest sample dimension, and is almost independent of the angle of the applied field. This behavior can be understood by considering the critical-state model when the applied field is at an arbitrary direction with respect to the sample axes.

The matrix elements of the up-spin and down-spin electronic density fluctuations taken between the ground state and the gapless elementary excitations of the Hubbard chain in a magnetic field are obtained. The small-ω charge and spin conductivity spectra are derived. Our results clarify the physical character of the pseudoparticles of the new Landau liquid theory, and identify them as the transport carriers. A generalized adiabatic continuity principle concerning the elementary excitations at finite magnetic field in the limit where momentum and frequency tend to zero is established.

We present a new scaling approach which allows one to map results obtained for isotropic superconductors to anisotropic materials in a simple and direct way. The scaling rules are obtained on the level of Ginzburg-Landau– or London–type equations and applied directly to the desired phenomenological quantity. We illustrate the method by calculating the elasticity moduli, the depinning and melting temperatures, the critical current densities, and the activation barriers for classical and quantum creep in anisotropic superconductors for an arbitrary angle between the magnetic field and the axes of anisotropy.

We report on flux-line pinning ${\mathrm{Bi}}_2$${\mathrm{Sr}}_2$${\mathrm{Ca}}_1$${\mathrm{Cu}}_2$${\mathrm{O}}_{\mathit{x}}$ crystals by a well-defined defect structure produced through 0.5-GeV iodine irradiation. Along their path these ions create columnar damage tracks of 5 to 10 nm in diameter. Even when flux lines are aligned parallel to these tracks, the measured activation energies at low temperatures and small fields do not exceed 70 meV and the critical currents decline rapidly with increasing temperature. The small pinning energies are explained quantitatively by pinning of two-dimensional pancake vortices instead of complete flux lines.

In situ, interference-enhanced Raman scattering of ultrathin, solid solution films of ${\mathrm{Rb}}_{\mathit{x}}$${\mathrm{C}}_{60}$ (0≤x≤3) prepared in UHV are reported. Variations of phonon linewidths of both selected low-frequency, radial and high-frequency, tangential intramolecular modes indicate strong electron-phonon coupling. The results directly support a recent theory for phonon-mediated superconductivity in alkali-${\mathrm{C}}_{60}$ systems.

The photoluminescence X-band optically deleted magnetic resonance (ODMR), ESR, and light-induced ESR (LESR) of ${\mathrm{C}}_{60}$ films and ${\mathrm{C}}_{60}$ in toluene/polystyrene glass (${\mathrm{C}}_{60}$:T/PS are described. The ESR at g=1.998 and delocalized triplet LESR and ODMR of ${\mathrm{C}}_{60}$:T/PS are similar to previously reported spectra. In films, the ODMR indicates that the delocalized triplet is larger and distorted by neighboring molecules. In addition, another, more localized triplet and a narrow photoluminescence-enhancing line at g=2.0017±0.0005, consistent with intermolecular polaron recombination, are also observed in films but not glasses.

We have reexamined type-I intermittency, i.e., alternating bursts of regular and chaotic behavior just preceding a tangent bifurcation of the quadratic map family. By studying period-3 intermittency for the Hénon map family numerically, we establish the strong one-dimensional character of intermittency in the phase space. The disappearance of intermittency as the one-dimensional character of the map is lost (i.e., the dissipation is decreased) is reflected in a qualitative change in the behavior of the Lyapunov exponent in the period-1 basin of attraction.

Ekert has described a cryptographic scheme in which Einstein-Podolsky-Rosen (EPR) pairs of particles are used to generate identical random numbers in remote places, while Bell’s theorem certifies that the particles have not been measured in transit by an eavesdropper. We describe a related but simpler EPR scheme and, without invoking Bell’s theorem, prove it secure against more general attacks, including substitution of a fake EPR source. Finally we show our scheme is equivalent to the original 1984 key distribution scheme of Bennett and Brassard, which uses single particles instead of EPR pairs.

If the standard model is extended to include two Higgs doublets and a singlet, there is a region of parameter space for which electromagnetism is broken in a narrow temperature range just below the electroweak transition temperature. In this range, the Universe superconducts, and monopoles will rapidly annihilate. It is shown that as the Universe passes through this temperature range, the abundance of monopoles will be depleted to acceptable levels, and, in addition, the process of annihilation could generate the observed baryon asymmetry.

We construct the minimal (most economical in fields) extension of the standard model implementing the Langacker-Pi mechanism for reducing the grand unified theory (GUT) monopole cosmic density to an allowed level. The model contains just a single charged scalar field in addition to the standard Higgs doublet, and is easily embeddable in any GUT. We identify the region of parameter space where monopoles annihilate in the higher temperature early Universe. A particularly alluring possibility is that the demise of monopoles at the electroweak scale is in fact the origin of the Universe’s net baryon number.