53 research outputs found
Magnetization, crystal structure and anisotropic thermal expansion of single-crystal SrEr2O4
The magnetization, crystal structure, and thermal expansion of a nearly
stoichiometric SrErO single crystal have
been studied by PPMS measurements and in-house and high-resolution synchrotron
X-ray powder diffraction. No evidence was detected for any structural phase
transitions even up to 500 K. The average thermal expansions of lattice
constants and unit-cell volume are consistent with the first-order Gr\"uneisen
approximations taking into account only the phonon contributions for an
insulator, displaying an anisotropic character along the crystallographic
\emph{a}, \emph{b}, and \emph{c} axes. Our magnetization measurements indicate
that obvious magnetic frustration appears below 15 K, and
antiferromagnetic correlations may persist up to 300 K.Comment: 6 pages, 5 figure, 2 table
CHIME : Cross-passage hierarchical memory network for generative review question answering
We introduce CHIME, a cross-passage hierarchical memory network for question answering (QA) via text generation. It extends XLNet introducing an auxiliary memory module consisting of two components: the context memory collecting cross-passage evidences, and the answer memory working as a buffer continually refining the generated answers. Empirically, we show the efficacy of the proposed architecture in the multi-passage generative QA, outperforming the state-of-the-art baselines with better syntactically well-formed answers and increased precision in addressing the questions of the AmazonQA review dataset. An additional qualitative analysis revealed the interpretability introduced by the memory module
Ensemble with estimation : seeking for optimization in class noisy data
Class noise, as know as the mislabeled data in training set, can lead to poor accuracy in classification no matter what machine learning methods are used. A reasonable estimation of class noise has a significant impact on the performance of learning methods. However, the error in estimation is inevitable theoretically. In this work, we propose an ensemble with estimation method to overcome the gap between the estimation and true distribution of class noise. Our proposed method does not require any a priori knowledge about class noises. We prove that the optimal classifier on the noisy distribution can approximate the optimal classifier on the clean distribution when the training set grows. Comparisons with existing algorithms show that our methods outperform state-of-the-art approaches on a large number of benchmark datasets in different domains. Both the theoretical analysis and the experimental result reveal that our method can improve the performance, works well on clean data and is robust on the algorithm parameter
Incommensurate antiferromagnetic order in the manifoldly-frustrated SrTbO with transition temperature up to 4.28 K
The Nel temperature of the new frustrated family of
Sr\emph{RE}O (\emph{RE} = rare earth) compounds is yet limited to
0.9 K, which more or less hampers a complete understanding of the
relevant magnetic frustrations and spin interactions. Here we report on a new
frustrated member to the family, SrTbO with a record =
4.28(2) K, and an experimental study of the magnetic interacting and
frustrating mechanisms by polarized and unpolarized neutron scattering. The
compound SrTbO displays an incommensurate antiferromagnetic (AFM) order
with a transverse wave vector \textbf{Q} = (0.5924(1),
0.0059(1), 0) albeit with partially-ordered moments, 1.92(6) at
0.5 K, stemming from only one of the two inequivalent Tb sites mainly by virtue
of their different octahedral distortions. The localized moments are confined
to the \emph{bc} plane, 11.9(66) away from the \emph{b} axis probably
by single-ion anisotropy. We reveal that this AFM order is dominated mainly by
dipole-dipole interactions and disclose that the octahedral distortion,
nearest-neighbour (NN) ferromagnetic (FM) arrangement, different next NN FM and
AFM configurations, and in-plane anisotropic spin correlations are vital to the
magnetic structure and associated multiple frustrations. The discovery of the
thus far highest AFM transition temperature renders SrTbO a new
friendly frustrated platform in the family for exploring the nature of magnetic
interactions and frustrations.Comment: 19 pages, 8 Figures, 1 Tabl
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