23,451 research outputs found
Competition between spin density wave order and superconductivity in the underdoped cuprates
We describe the interplay between d-wave superconductivity and spin density
wave (SDW) order in a theory of the hole-doped cuprates at hole densities below
optimal doping. The theory assumes local SDW order, and associated electron and
hole pocket Fermi surfaces of charge carriers in the normal state. We describe
quantum and thermal fluctuations in the orientation of the local SDW order,
which lead to d-wave superconductivity: we compute the superconducting critical
temperature and magnetic field in a `minimal' universal theory. We also
describe the back-action of the superconductivity on the SDW order, showing
that SDW order is more stable in the metal. Our results capture key aspects of
the phase diagram of Demler et al. (cond-mat/0103192) obtained in a
phenomenological quantum theory of competing orders. Finally, we propose a
finite temperature crossover phase diagram for the cuprates. In the metallic
state, these are controlled by a `hidden' quantum critical point near optimal
doping involving the onset of SDW order in a metal. However, the onset of
superconductivity results in a decrease in stability of the SDW order, and
consequently the actual SDW quantum critical point appears at a significantly
lower doping.
All our analysis is placed in the context of recent experimental results.Comment: 27 pages, 11 figures; (v2) added clarifications and refs, and
corrected numerical errors (thanks to A. Chubukov
Photonic band gap and x-ray optics in warm dense matter
Photonic band gaps for the soft x-rays, formed in the periodic structures of
solids or dense plasmas, are theoretically investigated. Optical manipulation
mechanisms for the soft x-rays, which are based on these band gaps, are
computationally demonstrated. The reflection and amplification of the soft
x-rays, and the compression and stretching of chirped soft x-ray pulses are
discussed. A scheme for lasing with atoms with two energy levels, utilizing the
band gap, is also studied.Comment: 3 figures, will be published on Po
X-ray Raman compression via two-stream instability in dense plasmas
A Raman compression scheme suitable for x-rays, where the Langmuir wave is
created by an intense beam rather than the pondermotive potential between the
seed and pump pulses, is proposed.
The required intensity of the seed and pump pulses enabling the compression
could be mitigated by more than a factor of 100, compared to conventionally
available other Raman compression schemes. The relevant wavelength of x-rays
ranges from 1 to 10 nm
Arkansas Wheat Cultivar Performance Tests 2016-2017
Wheat cultivar performance tests are conducted each year in Arkansas by the University of Arkansas System Division of Agriculture’s Arkansas Agricultural Experiment Station, Department of Crop, Soil and Environmental Sciences. The tests provide information to companies developing cultivars and marketing seed within the state and aid the Arkansas Cooperative Extension Service in formulating cultivar recommendations for small-grain producers
Arkansas Wheat Cultivar Performance Tests 2018-2019
Wheat cultivar performance tests are conducted each year in Ark- ansas by the University of Arkansas System Division of Agriculture’s Arkansas Agricultural Experiment Station, Department of Crop, Soil and Environmental Sciences. The tests provide information to companies developing cultivars and marketing seed within the state and aid the Arkansas Cooperative Extension Service in formulating cultivar recommendations for small-grain producers. The tests are conducted at the Northeast Research and Extension Center at Keiser, the Vegetable Substation near Kibler, the Lon Mann Cotton Research Station near Marianna, the Newport Extension Center near Newport, the Rohwer Research Station near Rohwer, the Pine Tree Research Station near Colt, and the Hope Research and Extension Center. In addition, entries are evaluated in a stripe rust (Puccinia striiformis f.sp. tritici) inoculated nursery in Fayetteville and a Fusarium head blight (FHB) inoculated nursery in Newport and Fayetteville. Specific location and cultural practice information accompany each table
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