cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.5286/isis.e.rb1510031
title: NEUTRON-INDUCED EFFECTS AND FAULT TOLERANCE IN MODERN PARALLEL AND HETEROGENEOUS ARCHITECTURES

description: We evaluate the resilience of modern parallel devices for high performance computing applications, i.e. Graphics Processing Units (GPUs), and heterogeneous Systems on Chips, i.e. Accelerated Processing Units. Nowadays the error rate of supercomputers may be extremely high. As we have evaluated with previous experiments at ISIS, the error rate of TITAN, a supercomputer composed of 18,000 GPUs, can be of up to one error every 10 minutes. TITAN personnel confirmed this value. Additionally, we were able to match experimental data gathered at ISIS with TITAN field data, based on more than 1,400 millions GB of data, and 500 millions GPU node hours of operation. Finally, we will study the neutron sensitivity of modern System on Chips embedding ARM core and FPGA programmable logic. We will exploit the FPGA programmability to implement a general-purpose mitigation scheme for the ARM processor.
DOI: 10.5286/isis.e.rb1510093
title: Direct measurement of the Au-D bond

description: Gold is historically thought of as an inert metal, and so investigation of its chemistry has been under-investigated. In 1986 it was shown that gold can be incredibly active as a catalyst when present as nanoparticles. The field has since grown rapidly, and the investigation of gold as a catalysts has increased hugely. Recently, the presence of hydrogen bonded to gold has been confirmed, and this study aims to use total neutron scattering to characterise this bond. Measurement using deuterium rather than hydrogen should be easier and allow determination of the bond length for the first time.
DOI: 10.5286/isis.e.rb1510178
title: C-H and H-H Binding in Coordinatively Unsaturated Ruthenium Carbene Complexes

description: Removal of the chloride ligand from the neutral N-heterocyclic carbene complex Ru(IPr)2(CO)HCl (IPr = bis(1,3-(2,6-diisopropylphenyl)imidazol-2-ylidene) by NaBArF4 affords the salt [Ru(IPr)2(CO)H]BArF4 (1), which has been characterised by X-ray crystallography as being stabilised by two agostic Ru...H-C interactions. Addition of an atmosphere of H2 traps this species to afford a spectroscopically characterised dihydrogen hydride complex, [Ru(IPr)2(CO)(eta2-H2)H]BArF4 (2). Neutron data will afford accurate measurement of both Ru...H-C and Ru(eta2-H2)H distances affording structural information crucial to understanding both the stoichiometric and potential catalytic reactivity (e. g. C=C/C=O hydrogenation) of these types of species.
DOI: 10.5286/isis.e.rb1510182
title: Exploring high energy nematic spin correlations in uniaxial-strained BaFe2As2

description: Electronic nematic phase in iron-pnictide superconductors have been discovered in various systems by techniques such as resistivity, ARPES, magnetic torque and neutron scattering. In this state, the electronic properties such as resistivity, spin excitation show anisotropy between (1 0) and (0 1) direction, even when the system is still in tetragonal phase. Our recent research of low energy spin excitations in detwinned BaFe2As2 shows nematic spin correlations persist to the tetragonal state, but it is unclear what happens at high energies.Given that the high energy spin waves in detwinned BaFe2As2 display two-fold rotational symmetry in our recent experiment on MERLIN, it is interesting to explore whether nematic fluctuations above Neel temperature will induce any nematicity in the high energy spin excitations dominated by superexchange coupling J between localized spins.
DOI: 10.5286/isis.e.rb1510357
title: Valence Bond Glass Formation as a function of temperature and composition in Ba2−xSrxLuMoO6

description: We request three days of beamtime on HRPD to study the crystallographic structures of six compounds containing a (distorted) frustrated antiferromagnetic lattice of Mo5+, 4d1 cations. Some of these compounds adopt a highly unusual spin−singlet valence bond state that is eliminated by structural distortion. Neutron diffraction will map the structural distortion as a function of composition and temperature and the data derived from these experiments will show which structural features are associated with the valence bond state.  Distortions in perovskites can be subtle and so the high resolution of HRPD and counting times of 4 hrs are necessary.  These compounds are also the subject of a proposal on EMU to use muons to examine the collapse of the valence bond state as a function of temperature and composition.
DOI: 10.5286/isis.e.rb1510482
title: Magnetic Excitations in SrRuO3

description: SrRuO3 is particularly interesting as it is the only simple Ruthenate that exhibits ferromagnetic order at ambient conditions, which still is a rare phenomenon in the broader class of transition metal oxides. Ferromagnetism in SrRuO3 is associated with strongly anomalous behavior in various properties of this material like the DC electronic transport yielding a linear resistivity showing bad metal behavior.Here we propose to study the high enery magnetic excitations using the time of flight neutron spectrometer Merlin.
DOI: 10.5286/isis.e.rb1510571
title: Spin-Lattice Coupling in spin ice Tb2Ti2O7

description: The rare earth titanates pyrochlores R2Ti2O7 are a topic of intense research focus owing to their perfect realisation of classical dipolar spin ice physics and the monopole excitations associated with this, as well as the possibility of observing more exotic behaviour such as spin liquids and the emergent electrodynamics associated with the quantum analogue of spin ice. Tb2Ti2O7 is a particularly challenging member of this series, because there are very low-lying crystal field levels which couple to phonons. It is believed that this coupling prevents the realisation of either the magnetic or structural phase transitions which are expected for this material, and instead result in an unusual spin-liquid ground state. Here, we propose to do the first detailed study of the phonon dispersions in this material, in order to place constraints on models which incorporate this unusual coupling.
DOI: 10.5286/isis.e.rb1600000
title: The magnetic structures of Ca2CoOsO6 and Sr2YOsO6
DOI: 10.5286/isis.e.rb1610344
title: Local field orientation and correlation length in the metal-organic perovskite copper guanidinium formate

description: In the metal-organic perovskite copper guanidinium formate, correlated Jahn-Teller distortion gives rise to a 1D magnetic structure made up of Heisenberg antiferromagnetic chains. We have previously shown that muSR experiments are capable of probing the correlation length in these chains. However, at least six muon sites are resolvable, and this complexity prevented us from measuring correlation lengths quantitatively. We therefore propose here angle-resolved muSR experiments in order to assign a local field orientation to each muon site, and hence to measure the correlation length directly as a function of temperature. Our results will be relevant to developing new materials for applications and fundamental physics as well as demonstrating a new way of extracting useful magnetic information from muSR data.
DOI: 10.5286/isis.e.rb1620019
title: Study of vibron stability in CeCuxAl4-x with x = 0.95 and 1.05

description: CeCuxAl4-x compounds crystallize in the ordered non-centrosymmeric tetragonal BaNiSn3-type structure (space group 107, I4mm). The strong interaction between crystal field (CF) excitons and phonon modes was observed in parent CeCuAl3. This type of interaction leads to the formation of so called vibron quasi-bound state, which has been observed as an additional peak in the inelastic neutron scattering spectra of only a few other Ce-based intermetallic compounds, e.g. CeAl2 or CePd2Al2. Our recent investigation of CeCuxAl4-x led to the observation of two clear crystal field-like peaks in all investigated compounds (x = 0.75, 0.9 and 1.1). We indent to focus on the development of CF-like excitations with slight Cu-Al substitution (x=0.95 and 1.05) to reveal their shift in energy coming further from stochiometric CeCuAl3.
DOI: 10.5286/isis.e.rb1620030
title: Crystal and Magnetic Structures of Unusually High Valence Fe Materials

description: Highly oxidized iron oxides such as SrFe4+O3, CaFe4+O3, and CaCu3Fe4O12 display unusual electronic and magnetic behaviors due to the highly covalent nature of the Fe-O interaction. Topochemical oxidation using high oxygen pressures leads to the formation of a new phase with composition Ca2FeCoO6. Magnetisation data show this material is ferrimagnetic with a transition temperature of approximately 220 K. We have used high temperatures and pressures to make oxygen stoichiometric Ca0.5Bi0.5FeO3 which shows novel charge ordering transitions at 200 and 250 K. We therefore request 2 days on GEM in order to characterize the two above materials. A standard 10-300 K CCR will be sufficient to record diffraction patterns as a function of temperature from a 1 g sample of Ca2FeCoO5 (~5 hours) and a 0.1 g sample of the high pressure Ca0.5Bi0.5FeO3 product (~43 hours).
DOI: 10.5286/isis.e.rb1620085
title: Investigation of non-Fermi liquid behaviour in Mn0.75Fe0.25Si through muon spin relaxation study

description: The investigation of electron correlations in intermetallic alloys is fascinating. At times, depending on the nature and strength of correlations, the compounds exhibit exotic/novel ground states. One such compound under the present investigation is Mn0.75Fe0.25Si. The bulk measurements like temperature and magnetic field dependence of specific heat, resistivity and susceptibility provide some knowledge about correlated nature of electrons. Importantly the microscopic origin of the strongly correlated nature can be probed through the muon spin relaxation technique. The current study contributes to advance the understanding of electron correlations in Mn0.75Fe0.25Si.
DOI: 10.5286/isis.e.rb1620201
title: MuSR search for fluctuating loop currents in cuprates

description: The origin of a mysterious pseudogap region in high-Tc superconductors is a challenging issue. It was proposed that the pseudogap is caused by a circulating-current order characterized by a unique long-range patten of loop currents in the CuO2 planes. Loop-current order is by now inferred in 5 different classes of symmetry-sensitive experiments: polarized neutron scattering, Kerr effect, bireferingence, dichroic ARPES, and second harmonic generation. However, local probes such as MuSR and NMR do not see the magnetic fields expected for such an order. These local probes have much longer time scales than the others. It has been suggested that the local magnetic fields may be motionally narrowed by fluctuations among the different possible directions of the loop-current order. We propose MuSR experiments to fairly definitively this possibility and also obtain the fluctuation time-scale.
DOI: 10.5286/isis.e.rb1620405
title: Strain Effects in Filled Rubber Nanocomposites (Continuation)

description: Our overall aim is to understand the origins of energy dissipation mechanisms in filled rubbers. These effects are responsible for much of the carbon footprint associated with road transport today. We have so far successfully used QENS and SANS to study the dynamics and structure of model silica filled polybutadiene nanocomposites. QENS shows little impact of crosslinking on dynamics, but a significant reduction in polymer mobility when silica nanoparticles are added.  We now focus on the dynamics of these systems whilst under an imposed strain, which mimics the process responsible for rolling resistance in tyres. In our refined setup, a motorised clamp and force transducer will allow QENS will be carried out on a series of filled rubber samples in which the filler and loading and applied stress and strain are systematically varied.
DOI: 10.5286/isis.e.rb1620425
title: Magnetic Phase Separation in a Frustrated Antiferromagnet

description: Frustrated magnetic materials are interesting because they show unusual behaviour arising from a near-degeneracy of ground states. The magnetic order of MgCr2O4 - apparently built from two symmetry-unrelated wavevectors - is an exotic example. Recent results suggest that magnetic order may involve frustration-induced phase separation into two nearly-degenerate states that couple differently to the lattice, leading to different lattice distortions from the cubic high-temperature phase. To test this hypothesis, we propose to use high-resolution powder and single-crystal diffraction to (i) determine if the magnetic structure is a single or two-phase; (ii) find the ordering wave vectors with respect to the low-temperature distorted crystal structure(s); (iii) solve the spin arrangements. Our results would reveal the nature of frustration and its coupling to the lattice in a topical magnet.
DOI: 10.5286/isis.e.rb1620441
title: Li-diffusion in anode material Li intercalated graphite for Li-ion battery

description: We would like to propose a muSR experiment on Li intercalated graphite, which is most commonly used for an anode material of Li-ion battery. With charging (discharging) reaction, Li is intercalated into (deintercalated from) graphite. In fully charged Li intercalated graphite, i.e., C6Li, Li locates between neighboring two sheets of graphene. This stracture is called Stage 1. C12Li has a stracture called Stage 2, where there are two layers of graphene between Li layer. In Li intercalated graphite CxLi with 6
DOI: 10.5286/isis.e.rb1670540
title: An Attempt To Unravel Critical Behavior in 1:2 TCNQ Salts TEA(TCNQ)2 and MEM(TCNQ)2
DOI: 10.5286/isis.e.rb1700003
title: Inelastic scattering from zinc oxide by neutron Laue diffraction
DOI: 10.5286/isis.e.rb1700082
title: ChipIr soft error calibration run

description: Initial ChipIr calibration run with devices tested before at other facilities. Get a feel for the beamline, setup area, setup, transportation to and from facility etc in preparation for future (hopefully) usage of the beamline for testing our equipment (or which we do several times per year to improve the reliability of our equipment that we build).
DOI: 10.5286/isis.e.rb1710004
title: Optimising graphene-philic surfactants as effective stabilizer for graphene production via electrochemical exfoliation method

description: Graphene has been touted as a material of everything, but for all its promise it does have some drawbacks, especially in its poor dispersibility and instability in water (and many common solvents); this limits any applications. Current techniques such as chemical vapour deposition (CVD) and mechanical exfoliation do produce high quality graphene films. However, these methods are not suitable for bulk material applications. A low-cost process to generate graphene by exfoliating graphite layers utilizing surfactant  may result in readily-dispersed graphene that can find applications in polymer composites.  For this proposal, a new range of surfactants have been systematically synthesised with the aims to explore how to design surfactants which can efficiently stabilize graphene so that it can be effectively applied for nanocomposite applications.
DOI: 10.5286/isis.e.rb1710018
title: Transition from Contact to Solvent-Separated Ion Pairs in protic ionic liquid/molecular liquid mixtures

description: Among the most important features affecting the behaviour of Ionic Liquids (IL) and their mixtures with molecular liquids (ML), ion pairing is attracting a great attention. This is the outcome of a delicate balance between ion-solvent and cation-anion interactions and in protic ILs (PILs) these involve not only coulombic and dispersive interactions, but also hydrogen bonding ones. Recently reports describing the transition from Contact Ion Pairs to solvent separated ones in PILs mixed with ML with different polarity have appeared. When MLs with high enough polarity are mixed with PILs, indirect spectroscopic evidences of this transition have been observed. So far no direct structural evidence of such a transition (and of its absence when considering less polar MLs) has been provided. With this proposal, we ask for SANDALS beam time to explore such an issue on different PIL/MLs
DOI: 10.5286/isis.e.rb1710377
title: Single crystal measurement of the magnetic fluctuations in triclinic Cu3Nb2O8:

description: Cu3Nb2O8 is a helicoidal magnet which is also multiferroic and displays coupling between structural and magnetic chirality.  In this proposal we propose to measure the magnetic fluctuations using MERLIN.  Merlin is required because the the magnetic order occurs at an incommensurate wavevector in all three directions.  A fully reciprocal space measurement is required.  We have also observed a sharp magnetic excitations at ~ 30 meV on MARI.  Using Merlin and the multi-rep rate feature, we can measure this excitation and the low energy fluctuations in a single experiment.
DOI: 10.5286/isis.e.rb1710404
title: High resolution powder diffraction on Sm based pyrochlores

description: Magnetic frustration is a hot topic in solid state physics, mainly due to the topological new phases of matter that frustration mechanisms can drive (vide Physics Nobel Prize 2016). We focus our research on the cubic Fd-3m, Sm2B2O7 pyrochlore coumpounds (B=Ti, Zr, Sn).  Mainly due to the the Samarium high absorption cross section, no studies of Sm compounds using neutrons are reported in literature. We have synthesised 154 Sm isotope enriched samples, what overcome this problem in a great extent. After x-ray diffraction and bulk characterisations of our sample, we believe that structure refinements of high resolution neutron diffraction data is the missing prove of our sample correct stoichiometry, especially on what concerns oxygens vacancies and ion substitutions. Those two factors are known to play a crucial role in the magnetic frustration at low temperatures.
DOI: 10.5286/isis.e.rb1410167
title: 1410167
DOI: 10.5286/isis.e.rb1510006
title: Crystal and magnetic structures of new layered perovskites of possible oxygen storage compounds LaBaFeMnO5 and LaBaFeMnO6

description: New layered perovskite compounds LaBaFeMnO5 and LaBaFeMnO6 were recently synthesized. They may be useful for future oxygen storage applications. Fe-Mössbauer spectroscopy has revealed that Fe3+ spins in LaBaFeMnO5 are antiferromagnetically ordered at 300 K while spin ordering for LaBaFeMnO6 is below room temperature. Precise determination of Fe-Mn ordering at the B sites, taking advantage of the high scattering contrast (b(Fe/Mn) = 9.5/-3.7 fm), and oxygen occupancy are crucial for the study of present materials. It is also very important to determine the detailed magnetic structures to understand the physical properties. We request 3 days on WISH to follow the temperature evolution of the crystal structure and magnetic order in the new LaBaFeMnO5 and LaBaFeMnO6 compounds.
DOI: 10.5286/isis.e.rb1510077
title: Origin of co-nonsolvency, based on the Flory-Huggins interaction parameters of PDEA in deuterated water/ethanol mixtures

description: Co-solvency and Co-nonsolvency are two extreme phenomena in the field of polymer solution. The former is the phenomenon that a mixture of two nonsolvent forms a good solvent for a polymer, and the latter is the reverse rare phenomenon that the solubility of polymer in a mixture of good solvents vanishes. The origin of co-nonsolvency has been debated for decades. The argument now is concentrating on whether or not the mixed solvent structure can influence polymer solubility. To clarify this, we propose to use poly(n,n¿-diethyl acrylamide) (PDEA) water/ethanol solution as a model system, and small angle neutron scattering (SANS) as the main tool to reveal the origin of co-nonsolvency. From the three Flory-Huggins interaction parameters in the model system, contribution of mixed solvent structure in the solubility of PDEA can be evaluated as a function of d-ethanol content and temperature.
DOI: 10.5286/isis.e.rb1510183
title: Does spinodal dewetting proceed by peristalsis?

description: We shall demonstrate the use of neutron reflectometry to obtain three-dimensional structures in a non-invasive experiment. Spinodal dewetting is one of the few areas where peristalsis (the mechanism by which the digestive tract moves food) occurs in the physical science. Here, a film spontaneously ruptures due to long-range forces, which act across the film. We propose to study a three-layered structure of poly(methyl methacrylate) sandwiched between two polystyrene layers, with the polymers chosen to have matched viscosities, which makes the effect much more visible. Spinodal dewetting causes the capillary waves at the interfaces between the polymer layers to be amplified, which leads to rupture. The increase in these capillary waves can be detected by the off-specular reflection of neutrons. It is this new technology that we shall harness in order to demonstrate the effect.
DOI: 10.5286/isis.e.rb1510252
title: Anomalously slow magnetic relaxation in a multi-q helimagnetic phase of SrFeO3

description: Non-coplanar magnetic orders in metallic helimagnets have been of great interest since the discovery of a vortex-like spin-swirling object called "skyrmion" and the resulting topological Hall effect in MnSi. A cubic perovskite metallic oxide SrFeO3 has been recently investigated as another example showing complex helimagnetic orders and metallic conduction. Quite recently, we have discovered that this system shows a long-time relaxation of magnetization in the helimagnetic ground state after cooling the sample under applied magnetic field. We suggest the possibility that the slow magnetic relaxation in SrFeO3 is attributed to time-dependent deformation in the skyrmion-like topological spin texture. In this proposal, we propose to perform time-resolved neutron diffraction measurements on SrFeO3 to directly observe the changes in magnetic structure.
DOI: 10.5286/isis.e.rb1510283
title: Dipolar Ordering of a High Spin Molecular Nanomagnet

description: Systems with antiferromagnetic ordering that is driven predominantly by dipolar interactions are very rare, as the dipolar interaction is inherently weak compared to the exchange interactions that are usually very much stronger. The single molecule magnet system Fe19 however provides a very good example of such a dipolar-driven antiferromagnet with a transition temperature of 1.2 K. This relatively high transition temperature for such a system makes it particularly suitable for detailed studies of critical properties of the dipolar ordering.  Further favourable properties of Fe19 relate to its ¿dipolar bias¿ that helps it to avoid spin freezing into a non-equilibrium state that can be a problem for other single molecule magnets. This neutron proposal builds on our previous muSR and Monte Carlo studies and aims to confirm the details of the magnetic ordering and test its criticality.
DOI: 10.5286/isis.e.rb1510287
title: A SANS study of nano-gels with a temperature tunable bio-interface

description: Hyaluronic acid (HA) plays a key role in tumour cell bio-adhesion and, as such, this interaction opens up possibilities for targeted tumour pathologies We have created a cross-linked hydrogel micro-particle targeting system based on HA-PNiPAAm. PNiPAAm induces a volume phase transition (VPT) at 36C above which the micro-particle ¿shrinks¿ and a core-shell structure emerges (hydrophilic HA covering hydrophobic PNiPAAm) Below 36C the chains mix randomly Micro-particle surface morphology is vital for effective cell adhesion yet little is know about how the surface structure of our system evolves as the VPT is crossed Such information would allow us to understand what the tumour cell ¿feels¿ on the particle surface To answer this question wish to perform SANS experiments (20, 40oC) using two gel types: one chemically and one physically cross-linked but both with a similar thermo-responsivity