13,175 research outputs found
Coexistence of superconductivity and antiferromagnetism in self-doped bilayer t-t'-J model
A self-doped bilayer t-t'-J model of an electron- and a hole-doped planes is
studied by the slave-boson mean-field theory. A hopping integral between the
differently doped planes, which are generated by a site potential, are
renormalized by the electron-electron correlation. We find coexistent phases of
antiferromagnetic (AFM) and superconducting orders, although the magnitudes of
order parameters become more dissimilar in the bilayer away from half-filling.
Fermi surfaces (FS's) with the AFM order show two pockets around the nodal and
the anti-nodal regions. These results look like a composite of electron- and
hole-doped FS's. In the nodal direction, the FS splitting is absent even in the
bilayer system, since one band is flat due to the AFM order.Comment: 6 pages, 4 figure
Interlayer couplings and the coexistence of antiferromagnetic and d-wave pairing order in multilayer cuprates
A more extended low density region of coexisting uniform antiferromagnetism
and d-wave superconductivity has been reported in multilayer cuprates, when
compared to single or bilayer cuprates. This coexistence could be due to the
enhanced screening of random potential modulations in inner layers or to the
interlayer Heisenberg and Josephson couplings. A theoretical analysis using a
renormalized mean field theory, favors the former explanation. The potential
for an improved determination of the antiferromagnetic and superconducting
order parameters in an ideal single layer from zero field NMR and infrared
Josephson plasma resonances in multilayer cuprates is discussed.Comment: 6 pages, 2 figure
Recommended from our members
Effects of contaminants of emerging concern on Megaselia scalaris (Lowe, Diptera: Phoridae) and its microbial community.
Drought, rising temperatures, and expanding human populations are increasing water demands. Many countries are extending potable water supplies by irrigating crops with wastewater. Unfortunately, wastewater contains biologically active, long-lived pharmaceuticals, even after treatment. Run-off from farms and wastewater treatment plant overflows contribute high concentrations of pharmaceuticals to the environment. This study assessed the effects of common pharmaceuticals on a cosmopolitan saprophagous insect, Megaselia scalaris (Diptera: Phoridae). Larvae were reared on artificial diets spiked with contaminants of emerging concern (CECs) at environmentally relevant concentrations. Female flies showed no oviposition preference for treated or untreated diets. Larvae exposed to caffeine in diets showed increased mortality, and larvae fed antibiotics and hormones showed signs of slowed development, especially in females. The normal sex ratio observed in M. scalaris from control diets was affected by exposure to caffeine and pharmaceutical mixture treatments. There was an overall effect of treatment on the flies' microbial communities; notably, caffeine fed insects displayed higher microbial variability. Eight bacterial families accounted for approximately 95% of the total microbes in diet and insects. Our results suggest that CECs at environmentally relevant concentrations can affect the biology and microbial communities of an insect of ecological and medical importance
Superconducting Pairing Symmetries in Anisotropic Triangular Quantum Antiferromagnets
Motivated by the recent discovery of a low temperature spin liquid phase in
layered organic compound -(ET)Cu(CN) which becomes a
superconductor under pressure, we examine the phase transition of Mott
insulating and superconducting (SC) states in a Hubbard-Heisenberg model on an
anisotropic triangular lattice. We use a renormalized mean field theory to
study the Gutzwiller projected BCS wavefucntions. The half filled electron
system is a Mott insulator at large on-site repulsion , and is a
superconductor at a moderate . The symmetry of the SC state depends on the
anisotropy, and is gapful with symmetry near the
isotropic limit and is gapless with symmetry at small anisotropy
ratio.Comment: 6 pages, 5 figure
MgO barrier-perpendicular magnetic tunnel junctions with CoFe/Pd multilayers and ferromagnetic insertion layers
The authors studied an effect of ferromagnetic (Co20Fe60B20 or Fe) layer
insertion on tunnel magnetoresistance (TMR) properties of MgO-barrier magnetic
tunnel junctions (MTJs) with CoFe/Pd multilayer electrodes. TMR ratio in MTJs
with CoFeB/MgO/Fe stack reached 67% at an-nealing temperature (Ta) of 200
degree C and then decreased rapidly at Ta over 250 degree C. The degradation of
the TMR ratio may be related to crystallization of CoFe(B) into fcc(111) or
bcc(011) texture result-ing from diffusion of B into Pd layers. MTJs which were
in-situ annealed at 350oC just after depo-siting bottom CoFe/Pd multilayer
showed TMR ratio of 78% by post annealing at Ta =200 degree C.Comment: 12 pages, 4 figure
Learning skills : robotics technology in automotive powertrain assembly
The past 40 years have seen industrial robots establish their superiority over humans in most areas of manufacturing requiring endurance or repeatability. One important application domain, however, has so far lagged behind the industry’s expectations: mechanical assembly. As fast, precise and dependable as they are, traditional industrial robots just don’t seem able to perform certain assembly operations as well as a skilled human worker. A task as simple as screwing a light bulb into a lamp socket shows why. Applying the right amount of force and turning the bulb at just the right time, at exactly the right angle, is something a human does intuitively. How can a robot be programmed to do this? For robots to successfully emulate humans on an assembly line, they need to have force-sensing capability and exhibit compliance. They must be able to direct forces and moments in a controlled way, and react to contact information. New robot force control technology from ABB shows how
Multi-task multi-modality SVM for early COVID-19 Diagnosis using chest CT data
Since January 2020 Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID 19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website.
Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre - including this research content - immediately available in PubMed Central and other
publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains activePublishe
Phases of the 2D Hubbard model at low doping
We show that the planar spiral phase of the 2D Hubbard model at low doping,
x, is unstable towards a noncoplanar spin configuration. The novel equilibrium
state we found at low doping is incommensurate with the inverse pitch of the
spiral varying as x^(1/2), but nevertheless has a dominant peak in the
susceptibility at (\pi,\pi). Relevance to the NMR and neutron scattering
experiments in La_2-xSr_xCuO_4 is disccussed.Comment: 12 pages, emtex v.3.
- …