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Inelastic neutron scattering was used to study the effect of 5 and 40 mol% cholesterol on the lateral nanoscale dynamics of phospholipid membranes. By measuring the excitation spectrum at several lateral q (||) values (up to q (||) = 3 Å(-1)), complete dispersion curves were determined of gel, fluid and liquid-ordered phase bilayers. The inclusion of cholesterol had a distinct effect on the collective dynamics of the bilayer's hydrocarbon chains; specifically, we observed a pronounced stiffening of the membranes on the nanometer length scale in both gel and fluid bilayers, even though they were experiencing a higher degree of molecular disorder. Also, for the first time we determined the nanoscale dynamics in the high-cholesterol liquid-ordered phase of bilayers containing cholesterol. Namely, this phase appears to be "softer" than fluid bilayers, but better ordered than bilayers in the gel phase.

High-temperature (high-Tc) superconductivity in the copper oxides arises from electron or hole doping of their antiferromagnetic (AF) insulating parent compounds. The evolution of the AF phase with doping and its spatial coexistence with superconductivity are governed by the nature of charge and spin correlations and provide clues to the mechanism of high-Tc superconductivity. Here we use a combined neutron scattering and scanning tunneling spectroscopy (STS) to study the Tc evolution of electron-doped superconducting Pr0.88LaCe0.12CuO4-delta obtained through the oxygen annealing process. We find that spin excitations detected by neutron scattering have two distinct modes that evolve with Tc in a remarkably similar fashion to the electron tunneling modes in STS. These results demonstrate that antiferromagnetism and superconductivity compete locally and coexist spatially on nanometer length scales, and the dominant electron-boson coupling at low energies originates from the electron-spin excitations., Comment: 30 pages, 12 figures, supplementary information included

As interest in low-temperature physics increases, whether for the study of frustrated magnets or for quantum effects, neutron spin-echo will become increasingly important, because of the high-energy resolution achievable. The behaviour of quasielastic scattering for low temperatures relative to the energy scale of interest is investigated. In addition, we note that momentum-transfer selective magnetic scattering may be susceptible to parasitic echoes in certain experimental configurations.

This topical review presents results from neutron inelastic scattering experiments on single crystals of UPd2Al3. The focus is on the experimental situation, while the sequel paper advances theoretical perspectives. We present a detailed and complete characterization of the wavevector- and energy-dependent magnetization dynamics in UPd2Al3 as measured by neutron inelastic scattering primarily in the form of extensive surveys in energy–momentum space under a wide range of experimental conditions, and put our observations in context with data that has been published previously by two independent groups. In this way we emphasize the robustness of the results, which indicate the intricate nature of the dynamic magnetic susceptibility of this material. This study yields unique insight into the low-temperature ground state, which exhibits a microscopic coexistence of antiferromagnetism and superconductivity, making UPd2Al3 one of the most accessible heavy-fermion superconductors that can be fully characterized by neutron spectroscopy.

Neutronen sind elektrisch neutral und haben ein magnetisches Moment. Deshalb eignen sie sich besonders zur Aufklarung der Struktur und Bewegung der Atome und der magnetischen Momente im Festkorper. Forscher am Institut Laue-Langevin konnten mit der Neutronen-Flugzeitspektroskopie die Rolle der Gitterschwingungen im Supraleiter Magnesium-Diborid aufklaren. Diffraktion mit polarisierten Neutronen kann die raumliche Verteilung der Magnetisierungsdichte zum Beispiel in einem Nanomagneten sichtbar machen. Neutronen-Dreiachsspektroskopie und -Kleinwinkelstreuung offnen den Zugang zum Wechselspiel zwischen Magnetismus und Supraleitung in Hochtemperatur- und Schwere-Fermionen-Supraleitern.

Neutron spectroscopy investigations into the magnetic dynamical response of the heavy Fermion superconductor UPd2Al3 support the notion of an interplay between magnetism and superconductivity in strongly correlated f-electron systems. After introducing the scientific framework we review the neutron experiments performed over the last few years. These studies highlight the experimental challenges and allow us to identify the instrumental requirements for such investigations. We conclude our paper on the recent technical achievements as well as future developments for three-axis spectroscopy (TAS) at the ILL.

More than eighty scientists gathered together for a workshop on the perspectives in Single Crystal Neutron Spectroscopy (SCNS) from December 12–14, 2002 at the Institut Laue-Langevin, Grenoble, France. Experts in both triple-axis spectroscopy (TAS) and time-of-flight (TOF) instrumentation, as well as condensed matter and material scientists, contributed to the meeting, which was organized jointly by the ILL and its collaborating research groups of the CEA/Grenoble and the FZ Julich with support from the Neutron Round Table and the City of Grenoble.