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Small Angle Neutron Scattering has been used to observe diffraction from the flux line lattice in the fully isotropic (K, Ba)BiO3high Tcsuperconductor. We show that the flux lines are ordered into a hexagonal lattice at low field (H < He∼ 0.6T ≪ Hg (0) where Hgis the second order vortex glass transition field). The diffracted intensity continuously drops to zero as the field is increased towards He. Those observations are in good agreement with recent theoritical works which suggested that the formation of dislocations becomes favorable above Heleading to a glassy structure. The field Helies close to the onset of the second peak in magnetization measurements indicating that this peak is related to the change in the vortex structure.

The phenomenon of superconductivity continues to be of considerable scientific and practical interest. Underlying this phenomenon is the formation of electron pairs, which in conventional superconductors do not rotate about their centre of mass (‘s -wave’ pairing; refs 1, 2). This contrasts with the situation in high-temperature superconductors, where the electrons in a pair are believed to have two units of relative angular momentum (‘d -wave’ pairing; ref. 3 and references therein). Here we report small-angle neutron-scattering measurements of magnetic flux lines in the perovskite superconductor Sr2RuO4 (ref. 4), which is a candidate for another unconventional paired electron state—‘p -wave’ pairing, which has one unit of angular momentum5,6,7. We find that the magnetic flux lines form a square lattice over a wide range of fields and temperatures, which is the result predicted by a recent theory8,9 of p -wave superconductivity in Sr2RuO4. This theory also indicates that only a fraction of the electrons are strongly paired and that the orientation of the square flux lattice relative to the crystal lattice will determine which parts of the three-sheet Fermi surface of this material are responsible for superconductivity. Our results suggest that superconductivity resides mainly on the ‘γ’ sheet9.

The lateral structures of dried adsorbed binary mixtures of star polymers were investigated. Blends of protonated and deuterated polybutadiene stars were prepared from cyclohexane solutions and adsorbed onto silicon substrates. The number of arms and the molecular weight of the arms was varied. With grazing incidence small angle scattering techniques (GISAS) and scanning force microscopy (SFM), different dominant in-plane length scales were determined. The morphology of these structures is dominated by blob-like structures created from single stars or agglomerates of star polymers.

Phase separation of the weakly incompatible blend system polystyrene and polyparamethylstyrene confined in isolated droplets is investigated. The droplet geometry imposes a two-dimensional spatial restriction. With specular, diffuse and grazing incidence small-angle neutron scattering the surface topography as well as the chemical morphology inside the droplets is determined. Due to the differences in surface tension, a core–shell-like structure characterized by one most prominent length scale inside the droplets is installed.

The reflectometer D17 has been operational for a year and has already proved to be an excellent tool for investigating surfaces and interfaces in the realms of physics, biology and chemistry. The instrument has two modes of operation, time-of-flight and monochromatic, the latter incorporating the polarised-neutron option. Both modes are flexible in the wave-vector-transfer (q) resolution. The loosest resolution required to resolve the sample structure can be chosen (and hence the highest flux), enabling the lowest reflectivities and hence the widest q-range to be measured.

Fluid Interfaces Grazing Angles ReflectOmeter (FIGARO) is the new horizontal neutron reflectometer at the Institut Laue-Langevin, Grenoble, France. It is a versatile, high-flux time-of-flight instrument with features suitable for a range of studies in soft condensed matter, chemistry, physics and biology both at free air/liquid interfaces and buried liquid/liquid and solid/liquid interfaces. Most of the experiments exploit isotopic contrast variation to determine the structure and composition of surface layers. Multiple chopper discs allow variable wavelength resolution, with the loose-resolution options increasing the available neutron flux for fast kinetic studies of thin films and improving the data acquisition efficiency from complex samples requiring multiple contrast measurements. It is possible to approach the interface with neutrons from below or above the horizon. The instrument is equipped with a range of sample environments including free liquid adsorption troughs, a Langmuir trough, an overflowing cylinder and a range of solid/liquid sample cells. FIGARO was launched as a user instrument in April 2009 and its success has been steadily increasing since. This article includes an introduction to the scientific case, detailed sections on the instrument components and performance, and descriptions of standard sample environments developed to date as well as some selected early scientific highlights.

Small-angle neutron studies have been performed on samples of continuous inhomogeneous magnetic recording media. This has allowed the local magnetic structure to be probed at a sub-nanometre resolution, revealing some interesting information about the size and shape of the magnetic grains and their relation to the physical grains.

Nature 396, 242–245 (1998) In this Letter, the X-ray Laue patterns used to give the orientation of our crystal were misinterpreted by 45°. With the magnetic field perpendicular to the RuO2 planes, the nearest-neighbour directions in the square flux-line lattice (FLL) are actually at 45° to the Ru–O–Ru directions in the crystal lattice.