183 research outputs found
Tuning the anomalous Nernst and Hall effects with shifting the chemical potential in Fe-doped and Ni-doped CoSnS
CoSnS is believed to be a magnetic Weyl semimetal. It displays
large anomalous Hall, Nernst and thermal Hall effects with a remarkably large
anomalous Hall angle. Here, we present a comprehensive study of how
substituting Co by Fe or Ni affects the electrical and thermoelectric
transport. We find that doping alters the amplitude of the anomalous transverse
coefficients. The maximum decrease in the amplitude of the low-temperature
anomalous Hall conductivity is twofold. Comparing our results
with theoretical calculations of the Berry spectrum assuming a rigid shift of
the Fermi level, we find that given the modest shift in the position of the
chemical potential induced by doping, the experimentally observed variation
occurs five times faster than expected. Doping affects the amplitude and the
sign of the anomalous Nernst coefficient. Despite these drastic changes, the
amplitude of the ratio at the Curie temperature
remains close to , in agreement with the scaling
relationship observed across many topological magnets.Comment: 8 pages, 9 figure
BOIN: An R Package for Designing Single-Agent and Drug-Combination Dose-Finding Trials Using Bayesian Optimal Interval Designs
This article describes the R package BOIN, which implements a recently developed methodology for designing single-agent and drug-combination dose-finding clinical trials using Bayesian optimal interval designs (Liu and Yuan 2015; Yuan, Hess, Hilsenbeck, and Gilbert 2016). The BOIN designs are novel "model-assisted" phase I trial designs that can be implemented simply and transparently, similar to the 3 + 3 design, but yield excellent performance comparable to those of more complicated, model-based designs. The BOIN package provides tools for designing, conducting, and analyzing single-agent and drug-combination dose-finding trials
4K-DMDNet: diffraction model-driven network for 4K computer-generated holography
Deep learning offers a novel opportunity to achieve both high-quality and high-speed computer-generated holography (CGH). Current data-driven deep learning algorithms face the challenge that the labeled training datasets limit the training performance and generalization. The model-driven deep learning introduces the diffraction model into the neural network. It eliminates the need for the labeled training dataset and has been extensively applied to hologram generation. However, the existing model-driven deep learning algorithms face the problem of insufficient constraints. In this study, we propose a model-driven neural network capable of high-fidelity 4K computer-generated hologram generation, called 4K Diffraction Model-driven Network (4K-DMDNet). The constraint of the reconstructed images in the frequency domain is strengthened. And a network structure that combines the residual method and sub-pixel convolution method is built, which effectively enhances the fitting ability of the network for inverse problems. The generalization of the 4K-DMDNet is demonstrated with binary, grayscale and 3D images. High-quality full-color optical reconstructions of the 4K holograms have been achieved at the wavelengths of 450 nm, 520 nm, and 638 nm
BARS: Towards Open Benchmarking for Recommender Systems
The past two decades have witnessed the rapid development of personalized
recommendation techniques. Despite significant progress made in both research
and practice of recommender systems, to date, there is a lack of a
widely-recognized benchmarking standard in this field. Many existing studies
perform model evaluations and comparisons in an ad-hoc manner, for example, by
employing their own private data splits or using different experimental
settings. Such conventions not only increase the difficulty in reproducing
existing studies, but also lead to inconsistent experimental results among
them. This largely limits the credibility and practical value of research
results in this field. To tackle these issues, we present an initiative project
(namely BARS) aiming for open benchmarking for recommender systems. In
comparison to some earlier attempts towards this goal, we take a further step
by setting up a standardized benchmarking pipeline for reproducible research,
which integrates all the details about datasets, source code, hyper-parameter
settings, running logs, and evaluation results. The benchmark is designed with
comprehensiveness and sustainability in mind. It covers both matching and
ranking tasks, and also enables researchers to easily follow and contribute to
the research in this field. This project will not only reduce the redundant
efforts of researchers to re-implement or re-run existing baselines, but also
drive more solid and reproducible research on recommender systems. We would
like to call upon everyone to use the BARS benchmark for future evaluation, and
contribute to the project through the portal at:
https://openbenchmark.github.io/BARS.Comment: Accepted by SIGIR 2022. Note that version v5 is updated to keep
consistency with the ACM camera-ready versio
Nonlinear charge transport induced by gate voltage oscillation in few-layer MnBi2Te4
Nonlinear charge transport, including nonreciprocal longitudinal resistance
and nonlinear Hall effect, has garnered significant attention due to its
ability to explore inherent symmetries and topological properties of novel
materials. An exciting recent progress along this direction is the discovery of
significant nonreciprocal longitudinal resistance and nonlinear Hall effect in
the intrinsic magnetic topological insulator MnBi2Te4 induced by the quantum
metric dipole. Given the importance of this finding, the inconsistent response
with charge density, and conflicting requirement of C3z symmetry, it is
imperative to elucidate every detail that may impact the nonlinear transport
measurement. In this study, we reveal an intriguing experimental factor that
inevitably gives rise to sizable nonlinear transport signal in MnBi2Te4. We
demonstrate that this effect stems from the gate voltage oscillation caused by
the application of a large alternating current to the sample. Furthermore, we
propose a methodology to significantly suppress this effect by individually
grounding the voltage electrodes during the second-harmonic measurements. Our
investigation emphasizes the critical importance of thoroughly assessing the
impact of gate voltage oscillation before determining the intrinsic nature of
nonlinear transport in all 2D material devices with an electrically connected
operative gate electrode.Comment: 28 pages, 12 figure
Single-shot deterministic complex amplitude imaging with a single-layer metalens
Conventional imaging systems can only capture light intensity. Meanwhile, the
lost phase information may be critical for a variety of applications such as
label-free microscopy and optical metrology. Existing phase retrieval
techniques typically require a bulky setup, multi-frame measurements, or prior
information of the target scene. Here, we proposed an extremely compact system
for complex amplitude imaging, leveraging the extreme versatility of a
single-layer metalens to generate spatially-multiplexed and
polarization-phase-shifted point spread functions. Combining the metalens with
a polarization camera, the system can simultaneously record four polarization
shearing interference patterns along both in-plane directions, thus allowing
the deterministic reconstruction of the complex amplitude light field in a
single shot. Using an incoherent light-emitting diode as the illumination, we
experimentally demonstrated speckle-noise-free complex amplitude imaging for
both static and moving objects with tailored magnification ratio and
field-of-view. The miniaturized and robust system may open the door for complex
amplitude imaging in portable devices for point-of-care applications
Two types of zero Hall phenomena in few-layer MnBiTe
The van der Waals antiferromagnetic topological insulator MnBiTe
represents a promising platform for exploring the layer-dependent magnetism and
topological states of matter. Despite the realization of several quantized
phenomena, such as the quantum anomalous Hall effect and the axion insulator
state, the recently observed discrepancies between magnetic and transport
properties have aroused controversies concerning the topological nature of
MnBiTe in the ground state. Here, we demonstrate the existence of two
distinct types of zero Hall phenomena in few-layer MnBiTe. In addition
to the robust zero Hall plateau associated with the axion insulator state, an
unexpected zero Hall phenomenon also occurs in some odd-number-septuple layer
devices. Importantly, a statistical survey of the optical contrast in more than
200 MnBiTe reveals that such accidental zero Hall phenomenon arises
from the reduction of effective thickness during fabrication process, a factor
that was rarely noticed in previous studies of 2D materials. Our finding not
only resolves the controversies on the relation between magnetism and anomalous
Hall effect in MnBiTe, but also highlights the critical issues
concerning the fabrication and characterization of devices based on 2D
materials.Comment: 21 pages, 4 figure
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