2,911 research outputs found
Depinning of elastic manifolds
We compute roughness exponents of elastic d-dimensional manifolds in
(d+1)-dimensional embedding spaces at the depinning transition for d=1,...,4.
Our numerical method is rigorously based on a Hamiltonian formulation; it
allows to determine the critical manifold in finite samples for an arbitrary
convex elastic energy. For a harmonic elastic energy, we find values of the
roughness exponent between the one-loop and the two-loop functional
renormalization group result, in good agreement with earlier cellular automata
simulations. We find that the harmonic model is unstable with respect both to
slight stiffening and to weakening of the elastic potential. Anharmonic
corrections to the elastic energy allow us to obtain the critical exponents of
the quenched KPZ class.Comment: 4 pages, 4 figure
Highly spin-polarized conducting state at the interface between non-magnetic band insulators: LaAlO3/FeS2 (001)
First-principles density functional calculations demonstrate that a
spin-polarized two-dimensional conducting state can be realized at the
interface between two non-magnetic band insulators. The (001) surface of the
diamagnetic insulator FeS2 (pyrite) supports a localized surface state deriving
from Fe d-orbitals near the conduction band minimum. The deposition of a few
unit cells of the polar perovskite oxide LaAlO3 leads to electron transfer into
these surface bands, thereby creating a conducting interface. The occupation of
these narrow bands leads to an exchange splitting between the spin sub-bands,
yielding a highly spin-polarized conducting state distinct from the rest of the
non-magnetic, insulating bulk. Such an interface presents intriguing
possibilities for spintronics applications.Comment: 5 pages, 5 figure
Modeling the iron oxides and oxyhydroxides for the prediction of environmentally sensitive phase transformations
Iron oxides and oxyhydroxides are challenging to model computationally as
competing phases may differ in formation energies by only several kJ/mol, they
undergo magnetization transitions with temperature, their structures may
contain partially occupied sites or long-range ordering of vacancies, and some
loose structures require proper description of weak interactions such as
hydrogen bonding and dispersive forces. If structures and transformations are
to be reliably predicted under different chemical conditions, each of these
challenges must be overcome simultaneously, while preserving a high level of
numerical accuracy and physical sophistication. Here we present comparative
studies of structure, magnetization, and elasticity properties of iron oxides
and oxyhydroxides using density functional theory calculations with plane-wave
and locally-confined-atomic-orbital basis sets, which are implemented in VASP
and SIESTA packages, respectively. We have selected hematite, maghemite,
goethite, lepidocrocite, and magnetite as model systems from a total of 13
known iron oxides and oxyhydroxides; and use same convergence criteria and
almost equivalent settings in order to make consistent comparisons. Our results
show both basis sets can reproduce the energetic stability and magnetic
ordering, and are in agreement with experimental observations. There are
advantages to choosing one basis set over the other, depending on the intended
focus. In our case, we find the method using PW basis set most appropriate, and
combine our results to construct the first phase diagram of iron oxides and
oxyhydroxides in the space of competing chemical potentials, generated entirely
from first principlesComment: 46 pages - Accepted for publication in PRB (19 journal pages),
January 201
Electrodeposition of Metals in Microgravity Conditions
Metal electrodeposition may introduce various morphological variations depending on the electrolytic conditions including cell configurations. For liquid electrolytes, a precise study of these deposits may be complicated by convective motion due to buoyancy. Zero-gravity (0-G) condition provided by drop shaft or parabolic flight gives a straightforward mean to avoid this effect: we present here 0-G electrodeposition experiments, which we compare to ground experiments (1-G). Two electrochemical systems were studied by laser interferometry, allowing to measure the concentration variations in the electrolyte: copper deposition from copper sulfate aqueous solution and lithium deposition from an ionic liquid containing LiTFSI. For copper, concentration variations were in good agreement with theory. For lithium, an apparent induction time was observed for the concentration evolution at 1-G: due to this induction time and to the low diffusion coefficient in ionic liquid, the concentration variations were hardly measurable in the parabolic flight 0-G periods of 20 seconds
Composition of Kinetic Momenta: The U_q(sl(2)) case
The tensor products of (restricted and unrestricted) finite dimensional
irreducible representations of \uq are considered for a root of unity.
They are decomposed into direct sums of irreducible and/or indecomposable
representations.Comment: 27 pages, harvmac and tables macros needed, minor TeXnical revision
to allow automatic TeXin
The Impact of Wine Tourism Involvement on Winery Owners' Identity Processes
This is an Accepted Manuscript of an article published by Taylor & Francis in Tourism Planning & Development on 20/02/2020, available online: doi: https://doi.org/10.1080/21568316.2020.1730945This paper examines how involvement in wine tourism has affected winery owners’ identity processes. Using Breakwell’s Identity Process Theory (IPT) as a conceptual framework, we investigate the extent to which place is a part of winery owners’ self-identities, thereby giving them senses of belonging, distinctiveness, continuity, and self-esteem. Simultaneously, we find that these senses and feelings influence winery owners’ perceptions of the benefits and dis-benefits of wine tourism development in their region. We also discover how personal involvement in tourism can strengthen or threaten winery owners’ identities and thereby affect their support or otherwise for wine tourism. Empirical evidence is provided via a sample of twenty-eight winery owners in Langhe, Italy, who have recently engaged in various tourism-related activities due to the continuous development of the local tourism industry. Our research recognises that place is an integral part of the identity process
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