[en] Desorption of O₂ in certain high-T_c superconductors was observed from scraping the surfaces of superconductors by Rosenberg and Wen. Their conclusion agrees with the results from the observation of O₂ trapping by a laser ablation of superconductors. However, the local heating due to the scraping process can possibly raise the local surface temperature significantly higher than the temperature of the bulk

[en] A recent theoretical prediction of the magnetic order to be expected in an erbium barium copper oxide high-temperature superconductor is shown to be based on questionable grounds

[en] By comparing data of the angular dependence of the remanent magnetization for a ceramic sample and for a single crystal of YBa₂Cu₃O₇ with similar demagnetization factors, we conclude that intrinsic anisotropy contributes significantly to anisotropic flux trapping in the crystal

[en] We present an alternate interpretation to the comments by P. Thalmeier [preceding paper, Phys. Rev. B 44, 7120 (1991)] based on the assumption that the antiferromagnetic transition is a secondary effect of some other phase transition at T_N [C. M. Varma (unpublished); see also Palstra et al., Phys. Rev. Lett. 55, 2727 (1985)]. This view is motivated by the observation that the ordered moment in URu₂Si₂ is very small (∼0.02μ_B) and similar to the ordered moment in UPt₃, another heavy-fermion system, and yet the specific-heat anomaly is at least 2 orders of magnitude larger in URu₂Si₂ than in UPt₃

[en] The choice of Pb as a counterelectrode is defended in high-T/sub c/ materials as well as the subsequent analysis of the NbN data

[en] It is pointed out that Stewart (Phys. Rev. B, to be published) is concerned with a series of approximations which are frequently made in practice, with good results for real materials

[en] Johnson comments that the states that our experiment found to have Δ₅ symmetry may consist of a linear combination of O 2p_z states. While this combination of states does exist, they will have large transverse wave numbers and cannot be detected in angle-resolved photoemission at normal emission, the conditions of our experiment

[en] We present another proof of the relationship that Leo and MacKinnon dispute

[en] Inelastic-scattering cross sections of 300--10 000-eV electrons in Si, Ti, Fe, and Pd and of 300--2000-eV electrons in Cu, Ag, and Au have been investigated theoretically and experimentally. The product of the inelastic mean free path and the cross section were determined experimentally through an analysis, based on a recent formula, of reflection electron-energy-loss spectra. To study energies above 2000 eV a special experimental setup was developed. Theoretical cross sections were determined through a dielectric-response description of the solid-electron interaction using Drude-Lindhard model dielectric functions. At high energies, good agreement is observed between theoretically and experimentally determined cross sections. At lower energies differences are observed. These are discussed partly in terms of a breakdown of the dielectric model used, and partly surface excitations

[en] Within the framework of the BCS pairing approximation, a theory of nonlinear electromagnetic rectification in a Cooper-paired jellium is established. It is pointed out that the electromagnetic rectification phenomenon, inevitably present as the many-body system's reaction in a second-harmonic generation process, is of special interest in a superconductor where induced dc currents flow without resistance. Based on a density-matrix approach the nonlinear response tensor is derived and discussed. The importance of nonlocality for the rectification process in centrosymmetric media is stressed. A simple expression for the response tensor is derived in the limit in which the nonlocal pairing effects are included to lowest order. It is demonstrated that electromagnetic rectification occurs only when the nonlinear response has a diamagnetic part. By considering the electromagnetic-rectification phenomenon as a nonlinear-dynamical Meissner effect, the relation to the linear Meissner effect is emphasized. A qualitative discussion of the rectification process at a superconductor-vacuum interface is undertaken. An integrodifferential equation describing, on the basis of the semiclassical infinite-barrier model, the diamagnetic screening of the nonlinear dc magnetic field is set up and discussed