46 research outputs found
Low-Thermal-Budget Ferroelectric Field-Effect Transistors Based on CuInP2S6 and InZnO
In this paper, we demonstrate low-thermal-budget ferroelectric field-effect
transistors (FeFETs) based on two-dimensional ferroelectric CuInP2S6 (CIPS) and
oxide semiconductor InZnO (IZO). The CIPS/IZO FeFETs exhibit non-volatile
memory windows of ~1 V, low off-state drain currents, and high carrier
mobilities. The ferroelectric CIPS layer serves a dual purpose by providing
electrostatic doping in IZO and acting as a passivation layer for the IZO
channel. We also investigate the CIPS/IZO FeFETs as artificial synaptic devices
for neural networks. The CIPS/IZO synapse demonstrates a sizeable dynamic ratio
(125) and maintains stable multi-level states. Neural networks based on
CIPS/IZO FeFETs achieve an accuracy rate of over 80% in recognizing MNIST
handwritten digits. These ferroelectric transistors can be vertically stacked
on silicon CMOS with a low thermal budget, offering broad applications in
CMOS+X technologies and energy-efficient 3D neural networks
One-ninth magnetization plateau stabilized by spin entanglement in a kagome antiferromagnet
The spin-1/2 antiferromagnetic Heisenberg model on a Kagome lattice is
geometrically frustrated, which is expected to promote the formation of
many-body quantum entangled states. The most sought-after among these is the
quantum spin liquid phase, but magnetic analogs of liquid, solid, and
supersolid phases may also occur, producing fractional plateaus in the
magnetization. Here, we investigate the experimental realization of these
predicted phases in the Kagome material YCu3(OD)6+xBr3-x (x=0.5). By combining
thermodynamic and Raman spectroscopic techniques, we provide evidence for
fractionalized spinon excitations and observe the emergence of a 1/9
magnetization plateau. These observations establish YCu3(OD)6+xBr3-x as a model
material for exploring the 1/9 plateau phase.Comment: to appear in Nature Physics, 33 pagses, 15 figure
Field-induced spin level crossings within a quasi-XY antiferromagnetic state in BaFeSiO
We present a high-field study of the strongly anisotropic easy-plane square
lattice = 2 quantum magnet BaFeSiO. This compound is a
rare high-spin antiferromagnetic system with very strong easy-plane anisotropy,
such that the interplay between spin level crossings and antiferromagnetic
order can be studied. We observe a magnetic field-induced spin level crossing
occurring within an ordered state. This spin level crossing appears to preserve
the magnetic symmetry while producing a non-monotonic dependence the order
parameter magnitude. The resulting temperature-magnetic field phase diagram
exhibits two dome-shaped regions of magnetic order overlapping around 30 T. The
ground state of the lower-field dome is predominantly a linear combination of
and states, while the ground state
of the higher-field dome can be approximated by a linear combination of and states. At 30 T, where the spin
levels cross, the magnetization exhibits a slanted plateau, {\color {black}the
magnetocaloric effect shows a broad hump, and the electric polarization shows a
weak slope change}. We determined the detailed magnetic phase boundaries and
the spin level crossings using measurements of magnetization, electric
polarization, and the magnetocaloric effect in pulsed magnetic fields to 60 T.
We calculate these properties using a mean field theory based on direct
products of SU(5) coherent states and find good agreement. Finally, we measure
and calculate the magnetically-induced electric polarization that reflects
magnetic ordering and spin level crossings. This multiferroic behavior provides
another avenue for detecting phase boundaries and symmetry changes.Comment: 9 pages, 5 figure
Facile and Universal Growth of Monolayer Transition Metal Dichalcogenides by Liquid-Phase Deposition
A scenario, goal and feature‐oriented domain analysis approach for developing software product lines
Interpolation time-optimized aortic pulse wave velocity estimation by 4D flow MRI
Abstract Four-dimensional flow magnetic resonance imaging-based pulse wave velocity (4D flow PWV) estimation is a promising tool for measuring regional aortic stiffness for non-invasive cardiovascular disease screening. However, the effect of variations in the shape of flow waveforms on 4D flow PWV measurements remains unclear. In this study, 4D flow PWV values were compared using cross-correlation algorithm with different interpolation times (iTs) based on flow rate and beat frequency. A critical iT (iTCrit) was proposed from in vitro study using flexible and stiff phantom models to simultaneously achieve a low difference and a low computation time. In vivo 4D flow PWV values from six healthy volunteers were also compared between iTCrit and the conventionally used interpolation time of 1 ms (iT1 ms). The results indicated that iTCrit reduced the mean difference of in vitro 4D flow PWV values by 19%, compared to iT1 ms. In addition, iTCrit measured in vivo 4D flow PWV, showing differences similar to those obtained with iT1 ms. A difference estimation model was proposed to retrospectively estimate potential differences of 4D flow PWV using known values of PWV and the used iT. This study would be helpful for understanding the differences of PWV generated by physiological changes and time step of obtained flow waveforms
Motion Artifact Reduction in Wearable Photoplethysmography Based on Multi-Channel Sensors with Multiple Wavelengths
Photoplethysmography (PPG) is an easy and convenient method by which to measure heart rate (HR). However, PPG signals that optically measure volumetric changes in blood are not robust to motion artifacts. In this paper, we develop a PPG measuring system based on multi-channel sensors with multiple wavelengths and propose a motion artifact reduction algorithm using independent component analysis (ICA). We also propose a truncated singular value decomposition for 12-channel PPG signals, which contain direction and depth information measured using the developed multi-channel PPG measurement system. The performance of the proposed method is evaluated against the R-peaks of an electrocardiogram in terms of sensitivity (Se), positive predictive value (PPV), and failed detection rate (FDR). The experimental results show that Se, PPV, and FDR were 99%, 99.55%, and 0.45% for walking, 96.28%, 99.24%, and 0.77% for fast walking, and 82.49%, 99.83%, and 0.17% for running, respectively. The evaluation shows that the proposed method is effective in reducing errors in HR estimation from PPG signals with motion artifacts in intensive motion situations such as fast walking and running