211 research outputs found
Exact physical quantities of a competing spin chain in the thermodynamic limit
We study the exact physical quantities of a competing spin chain which
contains many interesting and meaningful couplings including the nearest
neighbor, next nearest neighbor, chiral three spins, Dzyloshinsky-Moriya
interactions and unparallel boundary magnetic fields in the thermodynamic
limit. We obtain the density of zero roots, surface energies and elementary
excitations in different regimes of model parameters. Due to the competition of
various interactions, the surface energy and excited spectrum show many
different pictures from those of the Heisenberg spin chain.Comment: 19 pages, 7 figure
Destruction of Neel order and appearance of superconductivity in electron-doped cuprates by oxygen annealing process
We use thermodynamic and neutron scattering measurements to study the effect
of oxygen annealing on the superconductivity and magnetism in
PrLaCeCuO. Although the transition temperature
measured by susceptibility and superconducting coherence length increase
smoothly with gradual oxygen removal from the annealing process, bulk
superconductivity, marked by a specific heat anomaly at and the presence
of a neutron magnetic resonance, only appears abruptly when is close to
the largest value. These results suggest that the effect of oxygen annealing
must be first determined in order to establish a Ce-doping dependence of
antiferromagnetism and superconductivity phase diagram for electron-doped
copper oxides.Comment: 5 pages, 4 figures, accepted by Phys. Rev.
SdCT-GAN: Reconstructing CT from Biplanar X-Rays with Self-driven Generative Adversarial Networks
Computed Tomography (CT) is a medical imaging modality that can generate more
informative 3D images than 2D X-rays. However, this advantage comes at the
expense of more radiation exposure, higher costs, and longer acquisition time.
Hence, the reconstruction of 3D CT images using a limited number of 2D X-rays
has gained significant importance as an economical alternative. Nevertheless,
existing methods primarily prioritize minimizing pixel/voxel-level intensity
discrepancies, often neglecting the preservation of textural details in the
synthesized images. This oversight directly impacts the quality of the
reconstructed images and thus affects the clinical diagnosis. To address the
deficits, this paper presents a new self-driven generative adversarial network
model (SdCT-GAN), which is motivated to pay more attention to image details by
introducing a novel auto-encoder structure in the discriminator. In addition, a
Sobel Gradient Guider (SGG) idea is applied throughout the model, where the
edge information from the 2D X-ray image at the input can be integrated.
Moreover, LPIPS (Learned Perceptual Image Patch Similarity) evaluation metric
is adopted that can quantitatively evaluate the fine contours and textures of
reconstructed images better than the existing ones. Finally, the qualitative
and quantitative results of the empirical studies justify the power of the
proposed model compared to mainstream state-of-the-art baselines
Magnetic fluctuations in n-type high- superconductors reveal breakdown of fermiology
By combining experimental measurements of the quasiparticle and dynamical
magnetic properties of optimally electron-doped PrLaCeCuO
with theoretical calculations we demonstrate that the conventional fermiology
approach cannot possibly account for the magnetic fluctuations in these
materials. In particular, we perform tunneling experiments on the very same
sample for which a dynamical magnetic resonance has been reported recently and
use photoemission data by others on a similar sample to characterize the
fermionic quasiparticle excitations in great detail. We subsequently use this
information to calculate the magnetic response within the conventional
fermiology framework as applied in a large body of work for the hole-doped
superconductors to find a profound disagreement between the theoretical
expectations and the measurements: this approach predicts a step-like feature
rather than a sharp resonance peak, it underestimates the intensity of the
resonance by an order of magnitude, it suggests an unreasonable temperature
dependence of the resonance, and most severely, it predicts that most of the
spectral weight resides in incommensurate wings which are a key feature of the
hole-doped cuprates but have never been observed in the electron-doped
counterparts. Our findings strongly suggest that the magnetic fluctuations
reflect the quantum-mechanical competition between antiferromagnetic and
superconducting orders.Comment: 10 pages, 9 figures, 1 tabl
- …