cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.5286/isis.e.rb1510344
title: Multiband Superconductivity of Ta4Pd3Te16

description: Ta4Pd3Te16 is a recently discovered superconductor (Tc = 4.6K) that has been suggested to be an unconventional superconductor. Electronic structure calculations showing that in spite of the layered crystal structure the material is an anisotropic three dimensional metal. The Fermi surface contains prominent one and two dimensional features, including nested 1D sheets, a 2D cylindrical section and a 3D sheet. The electronic states that make up the Fermi surface are mostly derived from Te p states, with small Ta d and Pd d contributions. We want to perform the muon-spin rotation (µSR) study, both transverse field (TF) and zero field (ZF) to investigate microscopic superconducting properties of Ta4Pd3Te16. TF µSR provides sensitive measurements of the superconducting gap structure. ZF µSR is important to find out the time reversal symmetry is broken or preserved.
DOI: 10.5286/isis.e.rb1510430
title: Unconventional slow spin fluctuations in Ba122 iron-based superconductors

description: The iron-based superconductors are at the forefront of the research on unconventional superconductivity. The Barium-122 systems, doped with electrons, reveal a non-trivial behavior, above the superconducting transition (Tc), in nuclear magnetic resonance (NMR) relaxation times. 75As NMR spin-spin relaxation time in the normal phase of 122 iron-based superconductors shows very slow spin fluctuations, which are absent in the high temperature superconducting cuprates. Recent experiments show the presence of nematic charge fluctuations, in the same observed temperature/doping range.  We thereby propose a muon spin rotation experiment to characterize the spin fluctuations, in a zero field and transverse field environment, in order to extend our previous NMR study, carried out in a broad range of magnetic fields, as well as to investigate the in-plane anisotropy of such slow dynamics.
DOI: 10.5286/isis.e.rb1510450
title: Local coordination and vibrational properties of hydride-ions  in peculiar perovskite oxyhydrides

description: This proposal requests 5 days on TOSCA with the aim to investigate the compositional dependence (x) of the local coordination and vibrational properties of the novel class of hydride-ion conducting perovskite oxyhydrides BaTiO3-xHx (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, and 0.6), including one deuterated equivalent (BaTiO2.4D0.6). The results will be correlated/compared with the corresponding Raman/IR spectra, to be measured in our home laboratory, as well as with results obtained from first-principles phonon calculations. The combination of results should provide detailed information regarding the structure and hydride-ion vibrational dynamics in perovskite oxyhydrides and hence increase our understanding of these materials. In particular, the results should help in the analysis of future QENS studies targeted at elucidating the hydride-ion dynamics on a local- to intermediate length-scale.
DOI: 10.5286/isis.e.rb1510497
title: Methane hydrate formation in the presence of graphene oxide

description: In this proposal we wish to study in situ formation of methane hydrates in the presence of graphene oxide. The aim of this research is to enable us to understand how different types of particle effect the occurrence and rate of methane hydrate nucleation. Recent simulations have predicted that in the presence of hydrophilic particles, methane, and therefore hydrate, should prefer the bulk to interfacial region. Neutrons and NIMROD are essential for this work, as they will allow us probe the relevant length and timescales, and also to exploit H/D labelling of the methane. In our previously awarded experiments RB1320495, RB1410533 and RB1400022, we successfully studied systems containing planar clay minerals and weakly hydrophilic nanosperes. In this experiment we will study nucleation in the presence of a more hydrophobic particle, namely graphene oxide.
DOI: 10.5286/isis.e.rb1510548
title: Spin orientations in epitaxial Mn2Au films for antiferromagnetic spintronics

description: Mn2Au has garnered a lot of interest as a promising material for the new field of antiferromagnetic spintronics. The symmetry of the crystal and magnetic order, already established for bulk powder samples, holds prospects for electric control of AF spins using recently predicted Neel-order fields. However, in order to fully realise this potential it is essential to develop thin film versions of this material. Here we propose to investigate the spin structure in epitaxial Mn2Au films using neutron diffraction.
DOI: 10.5286/isis.e.rb1510585
title: Muon spin relaxation study on cobalt arsenides ACo2As2 (A = Ca, Sr and Ba)

description: Recent investigations of physical properties of ACo2As2 (A = Ca, Sr, Ba) indicate that Co-based arsenides could be a potential parent compound like the parent AFe2As2. While CaCo2As2 shows an A-type antiferromagnetism both SrCo2As2 and BaCo2As2 remains paramagnetic down to 1.3 K and 0.45 K, respectively. Inelastic neutron scattering reveal stripe spin fluctuations in SrCo2As2 similar to those found in parent AFe2As2. Because of high sensitivity of muons to extremely small magnetic field it would be of interest to investigate the magnetic correlations in SrCo2As2 and BaCo2As2 using muon spin relaxation (µSR) technique. We therefore propose to carry out µSR study on these two compounds using the MUSR spectrometer. For a comparative study we also plan to perform µSR study on CaCo2As2.
DOI: 10.5286/isis.e.rb1520133
title: A melanin-inspired pro-oxidant system for dopa(mine) polymerization: implication for the biological process and possible technological appli

description: Melanins are the major determinants of pigmentation of skin, hair and eyes in humans. These pigments originate from the tyrosinase-catalyzed oxidation of tyrosine, leading to the unstable 3,4-dihydroxyphenylalanine (DOPA) quinone that through polymerization produce a black insoluble eumelanins. Nucleophilic addition of cysteine to DOPA quinone produces alkali-soluble pheomelanins via 5-S-cysteinylDOPA (CD). This present study will provide the basis for the development of technologies to use CD-based polymers for implementation of eumelanin/polydopamine coatings. From a biological viewpoint, definition of the described processes will throw light on the mode of formation of melanosomes and melanized granules in neuromelanin and irides, unraveling a natural strategy to mask an oxidant active polymer of potential toxicity by growth of a pigment shell, which is expected to be less toxic.
DOI: 10.5286/isis.e.rb1520170
title: A hidden spin liquid state in strongly correlated FeCrAs

description: In this continuation proposal we will conclude our muon study of FeCrAs, a recently re-examined material that displays many of the above characteristics, suggesting that it is a strongly correlated electron system, but with a local physics dominated by complex antiferromagnetism, magnetic frustration and charge fluctuations.  By measuring a sample with a proven ultra-low degree of disorder, we will search for the proposed hidden spin-liquid phase in FeCrAs and measure the magnetic fluctuation spectrum over a wide temperature range.
DOI: 10.5286/isis.e.rb1520197
title: Static/dynamic disorder, ion migration and possible ferroelectricity in the hybrid halide perovskite CH3NH3PbI3 for PV applications

description: Solar cells based on a layer of halide perovskite have recently seen rapid increases in efficiency, with certified values in excess of 20%.  The prototypical material of this class is the methyl-ammonium-containing halide perovskite CH3NH3PbI3.  Very recently, the phase transitions and dynamic disorder of this structure, which has been extensively studied since the eighties, have come under renewed scrutiny, since they appear to be related to key PV performance parameters.  Here, we propose to study for the first time the Bragg and diffuse scattering from a fully deuterated crystal, using time-sorted Laue diffraction on SXD.  In addition to studying the average symmetry and the ion conduction pathways, this experiment, in combination with other techniques (see related OSIRIS proposal) will shed light on the dynamical molecular reorientation correlations in the different phases.
DOI: 10.5286/isis.e.rb1520201
title: Determining the magnetic structures of NaxCa1-xMn7O12 (x=0.25 and x=0.75): Candidate materials for novel orbital order and multiferroicity.

description: Several members of the AA'3Mn4O12 quadruple perovskite family have now been realised, and are known to support intricate charge, orbital, and magnetic ordering phenomena. In particular NaMn7O12 develops commensurate magnetic and orbital order, as in the well-known compound La0.5Ca0.5MnO3, whereas CaMn7O12 exhibits a more exotic incommensurate magneto-orbital helix. We have grown for the first time NaxCa1-xMn7O12 compounds with x=0.25, 0.5, and 0.75. These compounds may realise magnetic structures that bridge the gap between exotic magneto-orbital helices and the well established collinear, commensurate order. Here we propose a continuation WISH experiment, based upon successful measurements recently made on the x=0.5 sample, to solve the magnetic structures of the x=0.25 and x=0.75 compounds with the primary aim of understanding the full NaxCa1-xMn7O12 phase diagram.
DOI: 10.5286/isis.e.rb1520281
title: Oxygen deficiency in the quantum spin ice Tb2Ti2O7

description: Tb2Ti2O7 is one of two compounds identified as potential quantum spin ices. As with other oxide pyrochlores the properties depend sensitively on the oxygen content. Most previous studies have aimed to work with samples as close to being stoichiometric as possible. Changes in the properties of Tb2Ti2O7 and Dy2Ti2O7 with oxygen-deficiency have recently been established. Here we propose to study the microscopic magnetic properties of oxygen-deficient Tb2Ti2O7 to compare with the extensive literature on stoichiometric samples.
DOI: 10.5286/isis.e.rb1520287
title: A second generation 2D antiferromagnet investigated with muons

description: Low-dimensional quantum magnetism continues to be of great theoretical and experimental interest, as reduced dimensionality supports strong quantum fluctuations which can result in novel excitations and critical behaviour. Muons have been proven to be a powerful means of exploring magnetic critical behaviour and fluctuations in low-dimensional quantum magnets. Here we propose to investigate a newly realized  molecular 2D quantum Heisenberg antiferromagnet [Cu(pz)2(2-OHpy)2](PF6)2, which is likely to be one of the most ideal two-dimensional systems yet found.
DOI: 10.5286/isis.e.rb1520455
title: Characterising -Bond Interactions in Catalytically Active Ruthenium Complexes

description: An unusual agostic stabilised ruthenium boryl complex [Ru(IPr)2(CO)(Bcat)]+ (IPr = bis(1,3-(2,6-diisopropylphenyl)imidazol-2-ylidene; Bcat = catecholborane) has been characterised by X-ray crystallography. Neutron data will afford accurate measurement of the Ru-H-C distance and, as such, provide structural information that will facilitate understanding of the of how structure relates to the catalytic alkene hydroboration activity of this complex. In Ru(IMe4)2(PPh3)(HSiPh3)H2, an alternative form of sigma bonding that involves 2-Ph3SiH coordination has been evidenced by NMR spectroscopy and X-ray crystallography. Neutron diffraction studies on this complex will afford definitive data on Ru-H and Si-H positions, information vital to understanding the role of this species as an intermediate in the catalytic hydrodefluorination reactions. We request 14-15 days
DOI: 10.5286/isis.e.rb1600003
title: Characterisation of the on-top vibrational mode of the surface hydride in beta-PdH.
DOI: 10.5286/isis.e.rb1610156
title: Magnetic structure of Ce2Ni12As7 using neutron diffraction

description: The aim of the experiment is to characterize the magnetic structure of the compound Ce2Ni12As7 using neutron diffraction. At low temperatures the magnetic moments of the cerium atoms form an ordered structure which can be probed using magnetic neutron diffraction. In many Ce based magnetic materials the size of the ordered moments are very small, due to the strong electron-electron interactions and the effect these have on the magnetic properties are currently not well understood. The diffraction patterns measured at 300K will be compared to those measured at low temperatures down to 0.3K and the observation of additional peaks in the patterns will indicate that the magnetic moments form an ordered arrangement. The main objectives are to confirm the presence of magnetic ordering at low temperatures and to identify the ordered structure from the intensity and position of the peaks.
DOI: 10.5286/isis.e.rb1610430
title: Li(MeNH2)4: Poor Metal, Worse Metal, and Magnet

description: We request 2 days on GEM to determine the structure of crystalline Li(MeNH2)4: we will be preparing the fully deuterated analogue. Our investigations into the magnetic state of this expanded metal using EMU has revealed two magnetic transitions. The use of neutron diffraction will allow us to not only determine the structure of Li(MeNH2)4, which is currently not known, but also whether these magnetic transitions are associated with any structural phase transition. The existence of any reflections arising from magnetic ordering of the lowest phase will also be determined.
DOI: 10.5286/isis.e.rb1610524
title: Vibrational frequencies of light-induced photoisomers for optical data storage applications

description: Ruthenium-based SO2 complexes present attractive prospects for next-generation 3-D optical data storage. Light is absorbed by the SO2 group, causing its dark state geometry (0) to be perturbed such that it yields a photo-isomer (1). This binary register can be captured in single-crystals of these materials. Structural studies show that the local crystal-field environment around the SO2 group (the reaction cavity) governs their optical properties. This environment has both static and dynamic components, therefore complementing the structural study of this reaction cavity with its vibrational counterpart, would provide unique insights into our materials understanding of their optical properties.  We propose to characterize the SO2 group by simultaneous measurement of single crystal diffraction and Raman spectra on SXD.
DOI: 10.5286/isis.e.rb1620004
title: Spin dynamics of quantum spin liquid state in CaCu3(OH)6Cl2・0.6H2O

description: Recently we have succeeded in synthesizing a new kagome material, CaCu3(OH)6Cl2 0.6H2O. Single crystal X-ray measurements revealed that no site disorder between Ca and Cu sites and Cu ions form an almost perfect kagome lattice; nearest-neighbor bond length difference is only 0.02%. Both susceptibility and heat capacity measurements on CaCu3(OH)6Cl2 0.6H2O revealed that long-range magnetic order is absence down to 2 K in spite of a large Currie-Weiss temperature of -60 K. Thus, we believe that CaCu3(OH)6Cl2 0.6H2O is a new candidate for quantum spin liquid in a perfect kagome lattice antiferromagnet such as ZnCu3(OH)6Cl2 and ZnCu3(OH)6SO4. We propose to measure spin dynamics at various temperatures to understand the nature of the spin disordered ground state in CaCu3(OH)6Cl2 0.6H2O.
DOI: 10.5286/isis.e.rb1620181
title: Solid Acetone as a Benchmark for Muon Quantum Effects

description: Extreme muon quantum effects will be studied in the simple organic molecule acetone using ALC spectroscopy to determine the quantum averaged hyperfine parameters of the state formed by muon addition to a C=O bond. These measurements will span between the low temperature solid phase which is dominated by quantum motion of the muon and the high temperature liquid phase where thermally activated vibrations of the muon within the molecule produce a significant temperature dependent contribution to the isotropic hyperfine constant. The results will be used to develop and test computational methods for determining muon parameters that take these quantum and thermal averaging effects fully into account.
DOI: 10.5286/isis.e.rb1620188
title: Charge and magnetic order in an overdoped manganite

description: Perovskite manganites exhibit a plethora of competing phases that can be tuned with modest changes in external parameters such as temperature, magnetic field, pressure or chemical doping. The degenerate double exchange theory, with suitable choice of renormalised parameters, can explain the characteristics of these phases and where they appear in the phase diagram. Recent work on half-doped manganites has shown excellent agreement between this theory and experiments. We now plan to extend this comparison to the overdoped regime, which is comparatively poorly understood due to the difficulties of sample synthesis. BiMnO3 can be doped with Sr to give access to an unusually wide range of hole-doping, so we have chosen this system on which to focus crystal growth efforts. We seek to characterise the nature of the charge and magnetic order present in our single crystal samples
DOI: 10.5286/isis.e.rb1620259
title: Investigation of a frustrated quantum magnet with novel interaction scheme

description: SrCuTe2O6 consists of a 3-dimensional arrangement of spin-1/2 Cu ions that are coupled into network of isolated triangles,a highly frustrated hyperkagome lattice consisting of corner sharing triangles and antiferromagnetic chains through the 1st, 2nd and 3rd neighbor interactions respectively. Of these, the chain interaction dominates in SrCuTe2O6 while the other two lead to frustrated interchain coupling resulting in long range magnetic order (LRO) at a suppressed temperature. This is in contrast to ideal spin-1/2 antiferromagnetic chain which is expected to have a spin liquid ground state with no LRO and spinon excitations. Frustrated interchain coupling leads to weak LRO and modifies the low energy excitation spectrum in a way that reflects the underlying physics arising from the frustration. Therefore, we wish to explore the magnetic excitations of SrCuTe2O6 using LET spectrometer.
DOI: 10.5286/isis.e.rb1620274
title: High pressure charge transitions in PbCoO3

description: PbCoO3 used to be the missing link in the PbMO3 perovskite series. PbCoO3 was recently synthesized by the Azuma group using high-pressure synthesis at 12 GPa. NPD at JPARC shows that it has the exciting and unexpected valence distribution of Pb2+Pb4+3Co2+2Co3+2O12 where Pb in the A-site and Co in the B-site of perovskite ABO3 both have charge ordering leading to the so-called A-site ordered double perovskite structure. The complex Pb2+0.25Pb4+0.75Co2+0.5Co3+0.5O3 valence distribution is expected to change with perturbations such as pressure and chemical modifications. A preliminary high pressure SXRD experiment found a 0.5 % volume drop at 5 GPa. We think that this corresponds to a Pb-Co charge transfer, but it needs to be confirmed by NPD. We request 3 days on PEARL for an initial room temperature experiment from near ambient up to 10 GPa pressure.
DOI: 10.5286/isis.e.rb1620343
title: Neutron scattering studies of novel multiferroic materials

description: This project lies on the study of multiferroic materials in which both electric dipole order and magnetic order  coexist. These materials are of the potential for new technology and of great interest in fundamental research. The aim of the current proposal is to study the multiferroic properties of pyroxenes using a combination of neutron, Xray and muon techniques with a particular emphasis on neutron diffraction, from both single crystal and powder samples, to determine the magnetic structures of various pyroxenes and to uncover the connection between their refined structures and their multiferroic properties. Neutron diffraction experiments under high pressure will reveal the spin symmetry related to induced new magnetic phases and in turn
DOI: 10.5286/isis.e.rb1620432
title: Investigation of the magnetic phases of the charge transfer compound CuTCNQ

description: The charge transfer compound CuTCNQ (TCNQ = 7,7,8,8-Tetracyanoquinodimethane) exhibits switching between two electrical resistance states when subject to an electric field. It is known that the the material has two structural phases (I and II) each with very different electrical conductivities and magnetic properties. While the electrical properties of CuTCNQ has been investigated by many, the magnetic properties have attracted very little interest even though phase II is ferromagnetic below 10K while phase I is essentially diamagnetic.  We propose to use muon spin rotation/relaxation to investigate the magnetic properties of both phases of CuTCNQ. The  ferromagnetic transition in CuTCNQ-II will be studied in zero field and in longitudinal fields. CuTCNQ-I will be investigated in zero field to look for evidence of antiferromagnetically coupled radical spins bound to the TCNQ anions.
DOI: 10.5286/isis.e.rb1700007
title: Ex situ Study of glass formation from ion-exchanged Zeolite by INS
DOI: 10.5286/isis.e.rb1710284
title: Antiplasticizing effect of water in amorphous prilocaine

description: In glassforming organic materials, the addition of water usually has a direct plasticizing effect, visible in a lowering of the glass-transition temperature Tg upon hydration of the material (the lower the Tg the higher the relative water content). We have observed an antiplasticizing effect in a small molecule, prilocaine, caused by the addition of water. This shift in Tg has been observed both with Differential Scanning Calorimetry experiments and Broadband Dielectric Spectroscopy. The microscopic hydrating mechanisms underlying the macroscopic antiplasticizing effect upon the addition of water to prilocaine are still unknown. Here we propose to investigate the hydration structure of prilocaine in solution using neutron diffraction coupled with both EPSR and Molecular dynamics simulations.
DOI: 10.5286/isis.e.rb1710365
title: The effect of an applied electric field on the adsorption and desorption of surfactants

description: A major influence on particles and amphiphile adsorption, particularly for charged materials is the surface potential.  Recent experiments have shown that this can be manipulated artificially by applying electric potentials to e.g. silicon/silica/solution interfaces.  Surprising irreversible binding of an anionic surfactant was observed and the origin of this phenomenon will be determined by exploring behaviour of different surfactants using neutron reflectivity.  In particular we will explore the removal of cationic surfactants by applying a positive potential and changes in the adsorption isotherm when the 'natural' negative potential is increased.  This work will develop an understanding of the influence of applied fields and allow means to control modification of interfaces that will be of wide importance in many applications.
DOI: 10.5286/isis.e.rb1710462
title: Examining the structural effects of non-stoichiometry in lithium amide-imide

description: The solid solution between lithium amide and lithium imide plays important roles in both ammonia decomposition catalysis and solid state hydrogen storage. In order to understand the stoichiometry-dependent function of the system, an elucidation of the variation in the structure of the solid solution across the stoichiometry range between amide and imide is necessary. It has already been observed that there are significant differences in structure depending on the synthesis method used.  As part of a systematic investigation of the structure and properties of the lithium amide-imide solid solution, we request one day of experimental time on POLARIS to measure neutron powder diffraction data of a series of non-stoichiometric samples from this system. This will allow the development of structural models for non-stoichiometry in the system.