7,617 research outputs found
Dimensionless ratios: characteristics of quantum liquids and their phase transitions
Dimensionless ratios of physical properties can characterize low-temperature
phases in a wide variety of materials. As such, the Wilson ratio (WR), the
Kadowaki-Woods ratio and the Wiedemann\--Franz law capture essential features
of Fermi liquids in metals, heavy fermions, etc. Here we prove that the phases
of many-body interacting multi-component quantum liquids in one dimension (1D)
can be described by WRs based on the compressibility, susceptibility and
specific heat associated with each component. These WRs arise due to additivity
rules within subsystems reminiscent of the rules for multi-resistor networks in
series and parallel --- a novel and useful characteristic of multi-component
Tomonaga-Luttinger liquids (TLL) independent of microscopic details of the
systems. Using experimentally realised multi-species cold atomic gases as
examples, we prove that the Wilson ratios uniquely identify phases of TLL,
while providing universal scaling relations at the boundaries between phases.
Their values within a phase are solely determined by the stiffnesses and sound
velocities of subsystems and identify the internal degrees of freedom of said
phase such as its spin-degeneracy. This finding can be directly applied to a
wide range of 1D many-body systems and reveals deep physical insights into
recent experimental measurements of the universal thermodynamics in ultracold
atoms and spins.Comment: 12 pages (main paper), (6 figures
Uniaxial zero thermal expansion in low-cost Mn2OBO3 from 3.5 to 1250 K
Unique zero thermal expansion (ZTE) materials are valuable for use in
precision instruments, including electronics, aerospace parts, and engines.
However, most ZTE materials have a temperature range less than 1000 K under
which they do not expand. In this study, we present a uniaxial ZTE in the
low-cost Mn2OBO3 with a thermal expansion coefficient of =
-1.710^(-7) K-1 along the [h00] direction from 3.5 to 1250 K. The
monoclinic structure of Mn2OBO3 remains stable over the entire temperature
range in ambient conditions. Considerable thermal contraction on the BO3
trigonal planar and thermal expansion on the MnO6 octahedra combine to produce
uniaxial ZTE. No charge order-disorder transition, which could cause thermal
contraction, was observed up to 1250 K
Training A Multi-stage Deep Classifier with Feedback Signals
Multi-Stage Classifier (MSC) - several classifiers working sequentially in an
arranged order and classification decision is partially made at each step - is
widely used in industrial applications for various resource limitation reasons.
The classifiers of a multi-stage process are usually Neural Network (NN) models
trained independently or in their inference order without considering the
signals from the latter stages. Aimed at two-stage binary classification
process, the most common type of MSC, we propose a novel training framework,
named Feedback Training. The classifiers are trained in an order reverse to
their actual working order, and the classifier at the later stage is used to
guide the training of initial-stage classifier via a sample weighting method.
We experimentally show the efficacy of our proposed approach, and its great
superiority under the scenario of few-shot training
Poly[μ4-succinato-μ2-succinato-bis[diamminecopper(II)]]
In the title compound, [Cu(C4H4O4)(NH3)2]n, the Cu atom is coordinated by the N atoms of two ammonia molecules and four O atoms from three different succinate ligands in a highly distorted octahedral geometry. The Cu atom and the C and O atoms of the succinate ligands lie on a mirror plane. Two adjacent CuO4N2 octahedra share one common O–O edge, forming a Cu2O6N4 bioctahedron with a Cu⋯Cu separation of 3.524 (2) Å. Neighboring bioctahedra are connected by bis-unidentate succinate anions in the a-axis direction, while in the c-axis direction bioctahedra are connected by bis-bidentate succinate anions, leading to an infinite two-dimensional network structure. These networks are further connected along the a-axis direction by hydrogen bonds between ammonia ligands and carboxylate O atoms of neighboring network layers, forming a three-dimensional lamellar structure
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