1,705 research outputs found
Interface states and anomalous quantum oscillations in graphene hybrid structures
One- and two-layer graphene have recently been shown to feature new physical
phenomena such as unconventional quantum Hall effects and prospects of
supporting a non-silicon technological platform using epitaxial graphene. While
both one- and two-layer graphene have been studied extensively, continuous
sheets of graphene possessing both parts have not yet been explored. Here we
report a study of such graphene hybrid structures. In a bulk hybrid featuring
two large-area one- and two-layer graphene and an interface between them, two
sets of Landau levels and features related to the interface were found. In edge
hybrids featuring a large two-layer graphene with narrow one-layer graphene
edges, we observed an anomalous suppression in quantum oscillation amplitude
due to the locking of one- and two-layer graphene Fermi energies and emergent
chiral interface states. These findings demonstrate the importance of these
hybrid structures whose unique interface states and related phenomena deserve
further studies.Comment: 4 pages, 4 figure
Low-Temperature Glassy Response of Ultrathin Manganite Films to Electric and Magnetic Fields
The glassy response of thin films of La0.8Ca0.2MnO3 to external magnetic and
gated electrostatic fields in a field-effect geometry has been studied at low
temperatures. A hierarchical response with irreversible memory effects,
non-ergodic time evolution, aging and annealing behavior of the resistance
suggest that the dynamics are governed by strain relaxation for both electronic
and magnetic perturbations. Cross-coupling of charge, spin, and strain have
been exploited to tune the coercivity of an ultrathin manganite film by
electrostatic gating.Comment: 4 pages, 5 figure
Predesign study for a modern 4-bladed rotor for the NASA rotor systems research aircraft
Trade-off study results and the rationale for the final selection of an existing modern four-bladed rotor system that can be adapted for installation on the Rotor Systems Research Aircraft (RSRA) are reported. The results of the detailed integration studies, parameter change studies, and instrumentation studies and the recommended plan for development and qualification of the rotor system is also given. Its parameter variants, integration on the RSRA, and support of ground and flight test programs are also discussed
Electrostatic Tuning of the Superconductor-Insulator Transition in Two Dimensions
Superconductivity has been induced in insulating ultra-thin films of
amorphous bismuth using the electric field effect. The screening of
electron-electron interaction was found to increase with electron concentration
in a manner correlated with the tendency towards superconductivity. This does
not preclude an increase in the density of states being important in the
development of superconductivity. The superconductor-insulator transition
appears to belong to the universality class of the three dimensional XY model.Comment: Four pages, three figures. Revised slightly to reflect referees'
comment
Low-temperature glassy response of ultrathin La0.8ca0.2Mn03 films to electric and magnetic fields
The glassy response of ultrathin films of La0.8Ca0.2MnO3 in the mixed phase to external magnetic and gated electro-static fields have been studied at low temperatures. The response of the resistance to external fields provides direct evidence for a hierarchical energy landscape, with strong cross-couplings between spin and charge. Magnetic coercivity measurements indicate that strong magnetic disorder accompanies the mixed phase in these films. This magnetic disorder, and the resultant coercivity, can be decreased by cooling in a large magnetic field or by electrostatic gating
Stability Analysis of Asynchronous States in Neuronal Networks with Conductance-Based Inhibition
Oscillations in networks of inhibitory interneurons have been reported at various sites of the brain and are thought to play a fundamental role in neuronal processing. This Letter provides a self-contained analytical framework that allows numerically efficient calculations of the population activity of a network of conductance-based integrate-and-fire neurons that are coupled through inhibitory synapses. Based on a normalization equation this Letter introduces a novel stability criterion for a network state of asynchronous activity and discusses its perturbations. The analysis shows that, although often neglected, the reversal potential of synaptic inhibition has a strong influence on the stability as well as the frequency of network oscillations
Manipulating superconducting fluctuations by the Little-Parks-de Gennes effect in ultrasmall Al loops
The destruction of superconducting phase coherence by quantum fluctuations
and the control of these fluctuations have been a problem of long-standing
interest, with recent impetus provided by its relevance to the pursuit of very
high temperature superconductivity. Building on the work of Little and Parks,
de Gennes predicted more than three decades ago that superconductivity could be
destroyed near half-integer-flux quanta in ultrasmall loops with a side branch,
resulting in a destructive regime. We report the experimental observation of
this Little-Parks-de Gennes effect in Al loops prepared by advanced e-beam
lithography. We show that the effect can be used to restore the lost phase
coherence through side branches.Comment: 4 page
Unconventional quantum oscillations in mesoscopic rings of spin-triplet superconductor Sr2RuO4
Odd-parity, spin-triplet superconductor Sr2RuO4 has been found to feature
exotic vortex physics including half-flux quanta trapped in a doubly connected
sample and the formation of vortex lattices at low fields. The consequences of
these vortex states on the low-temperature magnetoresistive behavior of
mesoscopic samples of Sr2RuO4 were investigated in this work using ring device
fabricated on mechanically exfoliated single crystals of Sr2RuO4 by
photolithography and focused ion beam. With the magnetic field applied
perpendicular to the in-plane direction, thin-wall rings of Sr2RuO4 were found
to exhibit pronounced quantum oscillations with a conventional period of the
full-flux quantum even though the unexpectedly large amplitude and the number
of oscillations suggest the observation of vortex-flow-dominated
magnetoresistance oscillations rather than a conventional Little-Parks effect.
For rings with a thick wall, two distinct periods of quantum oscillations were
found in high and low field regimes, respectively, which we argue to be
associated with the "lock-in" of a vortex lattice in these thick-wall rings. No
evidence for half-flux-quantum resistance oscillations were identified in any
sample measured so far without the presence of an in-plane field.Comment: 5 pages, 4 figure
From ‘other’ to involved: User involvement in research: An emerging paradigm
This article has been made available through the Brunel Open Access Publishing Fund. Copyright @ 2013 The Author(s).
This is an Open Access article. Non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly attributed, cited, and is not altered, transformed, or built upon in any way, is permitted. The moral rights of the named author(s) have been asserted.This article explores the issue of ‘othering’ service users and the role that involving them, particularly in social policy and social work research may play in reducing this. It takes, as its starting point, the concept of ‘social exclusion’, which has developed in Europe and the marginal role that those who have been included in this construct have played in its development and the damaging effects this may have. The article explores service user involvement in research and is itself written from a service user perspective. It pays particular attention to the ideological, practical, theoretical, ethical and methodological issues that such user involvement may raise for research. It examines problems that both research and user involvement may give rise to and also considers developments internationally to involve service users/subjects of research, highlighting some of the possible implications and gains of engaging service user knowledge in research and the need for this to be evaluated
- …