654 research outputs found
A Non-Centrosymmetric Superconductor with a Bulk 3D Dirac Cone Gapped by Strong Spin Orbit Coupling
Layered, non-centrosymmetric, heavy element PbTaSe2 is found to be
superconducting. We report its electronic properties accompanied by electronic
structure calculations. Specific heat, electrical resistivity and magnetic
susceptibility measurements indicate that PbTaSe2 is a moderately coupled,
type-II BCS superconductor (Tc = 3.72 K, Ginzburg-Landau parameter Kappa = 14)
with an electronphonon coupling constant of Lambda_ep = 0.74. Electronic
structure calculations reveal a single bulk 3D Dirac cone at the K point of the
Brillouin Zone derived exclusively from its hexagonal Pb layer; it is similar
to the feature found in graphene except there is a 0.8 eV gap opened by
spin-orbit coupling. The combination of large spin-orbit coupling and lack of
inversion symmetry also results in large Rashba splitting on the order of
tenths of eV
Electronic structure basis for the titanic magnetoresistance in WTe
The electronic structure basis of the extremely large magnetoresistance in
layered non-magnetic tungsten ditelluride has been investigated by
angle-resolved photoelectron spectroscopy. Hole and electron pockets of
approximately the same size were found at the Fermi level, suggesting that
carrier compensation should be considered the primary source of the effect. The
material exhibits a highly anisotropic, quasi one-dimensional Fermi surface
from which the pronounced anisotropy of the magnetoresistance follows. A change
in the Fermi surface with temperature was found and a high-density-of-states
band that may take over conduction at higher temperatures and cause the
observed turn-on behavior of the magnetoresistance in WTe was identified
A Proposal to Detect Dark Matter Using Axionic Topological Antiferromagnets
Antiferromagnetically doped topological insulators (A-TI) are among the
candidates to host dynamical axion fields and axion-polaritons; weakly
interacting quasiparticles that are analogous to the dark axion, a long sought
after candidate dark matter particle. Here we demonstrate that using the axion
quasiparticle antiferromagnetic resonance in A-TI's in conjunction with
low-noise methods of detecting THz photons presents a viable route to detect
axion dark matter with mass 0.7 to 3.5 meV, a range currently inaccessible to
other dark matter detection experiments and proposals. The benefits of this
method at high frequency are the tunability of the resonance with applied
magnetic field, and the use of A-TI samples with volumes much larger than 1
mm.Comment: 6 pages, 4 figures. v2 accepted for publication in Physical Review
Letters. Many points clarified, some parameter estimates revise
Cd3As2 is Centrosymmetric
This is a revised version of a manuscript that was originally posted here in
February of 2014. It has been accepted at the journal Inorganic Chemistry after
reviews that included those of two crystallographers who made sure all the t's
were crossed and the i's were dotted. The old work (from 1968) that said that
Cd3As2 was noncentrosymmetric was mistaken, with the authors of that study
making a type of error that in the 1980s became infamous in crystallography. As
a result of the increased scrutiny of the issue of centrosymmetricity of the
1980's, there are now much better analysis tools to resolve the issue fully,
and its important to understand that not just our crystals are centrosymmetric,
even the old guy's crystals were centrosymmetric (and by implication everyone's
are). There is no shame in having made that error back in the day and those
authors would not find the current centrosymmetric result controversial; their
paper is excellent in all other aspects. This manuscript describes how the
structure is determined, explains the structure schematically, calculates the
electronic structure based on the correct centrosymmetric crystal structure,
and gives the structural details that should be used for future analysis and
modeling.Comment: Accepted by ACS Inorganic Chemistr
Correlation of Crystal Quality and Extreme Magnetoresistance of WTe
High quality single crystals of WTe were grown using a Te flux followed
by a cleaning step involving self-vapor transport. The method is reproducible
and yields consistently higher quality single crystals than are typically
obtained via halide assisted vapor transport methods. Magnetoresistance
(MR)values at 9 Tesla and 2 Kelvin as high as 1.75 million \%, nearly an order
of magnitude higher than previously reported for this material, were obtained
on crystals with residual resistivity ratio (RRR) of approximately 1250. The MR
follows a near B law (B = 1.95(1)) and, assuming a semiclassical model, the
average carrier mobility for the highest quality crystal was found to be
~167,000 cm/Vs at 2 K. A correlation of RRR, MR ratio and average carrier
mobility () is found with the cooling rate during the flux growth.Comment: 7 pages, 3 figures, 1 tabl
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Evaluating sustainable energy potentials through carbon emission assessment of small and medium-sized enterprises in the global south: a case in Wula, CRS Nigeria
There is increasing focus on sustainable energy in developing countries as part of their transition to low carbon economy. Approximately, 40% of the world’s population, mostly in low- and middle-income countries, do not have access to modern energy. Developing countries including Nigeria are facing energy poverty. Small and medium-sized enterprises (SMEs) have a role in achieving the United Nations’ (UN) Sustainable Development Goals (SDGs). Absence of sustainable energy is hindering the growth of SMEs in the Global South with impacts on society. In Nigeria, inaccessibility and regular outages of power from the national grid compels SMEs to rely on fossil-fuel based energy which exacerbate pollution and carbon footprint having environmental, social and economic consequences. This project evaluates the potential of sustainable energy in SMEs for minimizing carbon footprint and accelerating the energy transition in a local community of Wula, Nigeria. This exploratory investigation conducted semi-structured interviews with 16 SMEs to obtain data on energy consumption including energy type, quantity consumed and annual cost to estimate carbon footprint and identify sustainable energy needs.
The study found that there is significant potential for sustainable energy in the local community and joined-up approach in interventions cannot only address environmental issues but social issues in the local community. The analysis indicates that SMEs spend $13,563.4 annually on fossil fuel-based energy and consume 33,215 litres of petrol/annum; and an estimated carbon footprint of 76,891.0642 KgCO2e (equivalent of 76.89106 tCO2e) per annum. The project helps to understand state of the problem and plans to reduce CO2 emissions and sustain SMEs by installing sustainable energy systems based on the community needs and contribute towards the SDGs. This could open new markets and business opportunities for the poor in the rural area, hence lift families out of poverty and transform lives as a contribution towards SDGs
Technological Gap in Pineapple Cultivation in Dimapur District of Nagaland
The study was conducted to examine the technological gap in recommended cultivation practices of pineapple in Dimapur district of Nagaland. A total of 120 respondents were personally interviewed by the researcher using a pre-tested interview schedule. The result of technological gap revealed that the highest (100%) technological gap was found in recommended practices like planting time, treatment of planting materials, manure and fertilizers, intercultural operations, growth regulators and Insect Disease Management. And the lowest was found in recommended varieties with 0% technology gap.
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DOI: 10.47856/ijaast.2021.v08i8.00
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