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magnetic Switching Dynamics and Tunnel Magnetoresistance Effect Based on Spin-Splitting Noncollinear Antiferromagnet Mn_(3)Pt

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Chinese Physics Letters 2024年第4期41卷 132-138页

作者：朱蒙董建艇李新录郑凡星周晔吴琨张佳 School of Physics and wuhan national high magnetic field center Huazhong University of Science and TechnologyWuhan 430074China

In comparison to ferromagnets,antiferromagnets are believed to have superior advantages for applications in next-generation magnetic storage devices,including fast spin dynamics,vanishing stray fields and robust against external magnetic field,***,unlike ferromagnetic orders,which could be detected through tunneling magnetoresistance effect in magnetic tunnel junctions,the antiferromagnetic order(i.e.,Néel vector)cannot be effectively detected by the similar mechanism due to the spin degeneracy of conventional *** discovered spin-splitting noncollinear antiferromagnets,such as Mn_(3)Pt with momentum-dependent spin polarization due to their special magnetic space group,make it possible to achieve remarkable tunneling magnetoresistance effects in noncollinear antiferromagnetic tunnel *** first-principles calculations,we demonstrate that the tunneling magnetoresistance ratio can reach more than 800% in Mn_(3)Pt/perovskite oxides/Mn_(3)Pt antiferromagnetic tunnel *** also reveal the switching dynamics of Mn_(3)Pt thin film under magnetic fields using atomistic spin dynamic *** study provides a reliable method for detecting Néel vector of noncollinear antiferromagnets through the tunnel magnetoresistance effect and may pave its way for potential applications in antiferromagnetic memory devices.

关键词： tunneling magnetoresistance momentum

Unconventional room-temperature negative magnetoresistance effect in Au/n-Ge:Sb/Au devices

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Chinese Physics B 2024年第3期33卷 602-608页

作者：何雄杨凡黎牛浩峪王立峰易立志许云丽刘敏潘礼庆夏正才 Hubei Engineering Research center of Weak magnetic-field Detection College of ScienceChina Three Gorges UniversityYichang 443002China wuhan national high magnetic field center Huazhong University of Science and TechnologyWuhan 430074China

Non-magnetic semiconductor materials and their devices have attracted wide attention since they are usually prone to exhibit large positive magnetoresistance(MR)effect in a low static magnetic field environment at room ***,how to obtain a large room-temperature negative MR effect in them remains to be *** this paper,by designing an Au/n-Ge:Sb/Au device with metal electrodes located on identical side,we observe an obvious room-temperature negative MR effect in a specific 50 T pulsed high magnetic field direction environment,but not in a static low magnetic field *** the analysis of the experimental measurement of the Hall effect results and bipolar transport theory,we propose that this unconventional negative MR effect is mainly related to the charge accumulation on the surface of the device under the modulation of the stronger Lorentz force provided by the pulsed high magnetic *** theoretical analytical model is further confirmed by regulating the geometry size of the *** work sheds light on the development of novel magnetic sensing,magnetic logic and other devices based on non-magnetic semiconductors operating in pulsed high magnetic field environment.

关键词： magnetoresistance germanium-based devices pulsed high magnetic fields

Hole mobility enhancement in monolayer WSe2 p-type transistors through molecular doping

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Science China(Information Sciences) 2024年第6期67卷 207-213页

作者： Shiyuan LIU Xiong XIONG Xin WANG Xinhang SHI Ru HUANG Yanqing WU School of Integrated Circuits and Beijing Advanced Innovation center for Integrated Circuits Peking University wuhan national high magnetic field center and School of Integrated Circuits Huazhong University of Science and Technology

Two-dimensional （2D） transition metal dichalcogenide （TMDC） semiconductor materials exhibit extraordinary electrical properties,holding promise for the realization of next-generation complementary metal-oxide-semiconductor （CMOS） devices at ultimate ***,constrained by effective device doping strategies,the hole mobility and device performance of tungsten diselenide （WSe2） p-type transistors,especially monolayer chemical vapor deposition （CVD）-grown WSe2,have not met *** this paper,an effective performance enhancement of monolayer WSe2p-type transistor was achieved through a molecular doping *** monolayer WSe2directly on SiO2back-gated substrates and leveraging energy band alignment design,4-nitrobenzenediazonium tetrafluoroborate （4-NBD） molecular dopant with a concentration of 10 m M was utilized to modulate the Fermi level position of monolayer WSe2for hole *** devices demonstrated a more than 98%increase in hole mobility,reaching up to 97 cm2·V-1·s-1while maintaining the current on/off ratio of *** p-type WSe2transistors with 1μm channel length exhibit a high drive current surpassing 176μA·μm-1,exceeding previous CVD-WSe2devices with similar channel *** straightforward and effective approach to improving the electrical performance of WSe2transistors paves the way for advanced logic technologies based on transition metal dichalcogenide semiconductors.

关键词： CVD-grown WSe$_2$ molecular doping 4-NBD p-type transistors hole mobility

On the evolution and formation of discharge morphology in pulsed dielectric barrier discharge

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Plasma Science and Technology 2024年第4期26卷 101-113页

作者：陈星宇李孟琦王威逸张权治彭涛熊紫兰 State Key Laboratory of Advanced Electromagnetic Technology Huazhong University of Science and TechnologyWuhan 430074People’s Republic of China School of Physics Dalian University of TechnologyDalian 116024People’s Republic of China wuhan national high magnetic field center Huazhong University of Science and TechnologyWuhan 430074People’s Republic of China

The discharge morphology of pulsed dielectric barrier discharge(PDBD) plays important roles in its applications. Here, we systematically investigated the effects of the voltage amplitude,discharge gap, and O_(2)content on the PDBD morphology, and revealed the possible underlying mechanism of the U-shaped formation. First, the morphological evolution under different conditions was recorded. A unique U-shaped region appears in the middle edge region when the gap is larger than 2 mm, while the entire discharge region remains columnar under a 2 mm gap in He PDBD. The width of the discharge and the U-shaped region increase with the increase in voltage, and decrease with the increase of the gap and O_(2)content. To explain this phenomenon,a two-dimensional symmetric model was developed to simulate the spatiotemporal evolution of different species and calculate the electric thrust. The discharge morphology evolution directly corresponds to the excited-state atomic reduction process. The electric thrust on the charged particles mainly determines the reaction region and strongly influences the U-shaped *** the gap is less than 2 mm, the electric thrust is homogeneous throughout the entire region,resulting in a columnar shape. However, when the gap is larger than 2 mm or O_(2)is added, the electric thrust in the edge region becomes greater than that in the middle, leading to the U-shaped formation. Furthermore, in He PDBD, the charged particles generating electric thrust are mainly electrons and helium ions, while in He/O_(2)PDBD those that generate electric thrust at the outer edge of the electrode surface are mainly various oxygen-containing ions.

关键词： low-temperature plasma dielectric barrier discharge discharge morphology particle distribution electric thrust

Purity-dependent Lorenz number,electron hydrodynamics and electron-phonon coupling in WTe_(2)

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Science China(Physics,Mechanics & Astronomy) 2024年第8期67卷 153-158页

作者： Wei Xie Feng Yang Liangcai Xu Xiaokang Li Zengwei Zhu Kamran Behnia wuhan national high magnetic field center and School of Physics Huazhong University of Science and TechnologyWuhan 430074China Laboratoire de Physique et d’Etude des Matériaux(ESPCI-CNRS-Sorbonne Université)PSL University Paris 75005France

We present a study of electrical and thermal transport in Weyl semimetal WTe_(2)down to 0.3 *** Wiedemann-Franz law holds below 2 K and a downward deviation starts *** deviation is more pronounced in cleaner samples,as expected in the hydrodynamic picture of electronic transport,where a fraction of electron-electron collisions conserve *** are the dominant heat carriers and their mean-free-path does not display a Knudsen *** is presumably a consequence of weak anharmonicity,as indicated by the temperature dependence of the specific *** momentum exchange between phonons and electrons leads to quantum oscillations of the phononic thermal ***-Grüneisen picture of electron-phonon scattering breaks down at low temperature when Umklapp ph-ph collisions cease to be a sink for electronic flow of *** with semi-metallic Sb shows that normal ph-ph collisions are amplified by *** both semimetals,at cryogenic temperature,e-ph collisions degrade the phononic flow of energy but not the electronic flow of momentum.

关键词： thermal conductivity Wiedemann-Franz law electron hydrodynamics electron-phonon coupling

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Enhanced anomalous Hall effect in kagome magnet YbMn_(6)Sn_(6)with intermediate-valence ytterbium

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Chinese Physics B 2024年第5期33卷 43-50页

作者：李龙飞迟晟玮马文龙郭凯臻徐刚贾爽 International center for Quantum Materials School of PhysicsPeking UniversityBeijing 100871China wuhan national high magnetic field center and School of Physics Huazhong University of Science and TechnologyWuhan 430074China Interdisciplinary Institute of Light-Element Quantum Materials and Research center for Light-Element Advanced Materials Peking UniversityBeijing 100871China Hefei national Laboratory Hefei 230088China

We report on the magnetization and anomalous Hall effect(AHE)in the high-quality single crystals of the kagome magnet YbMn_(6)Sn_(6),where the spins of the Mn atoms in the kagome lattice order ferromagnetically and the intermediate-valence Yb atoms are *** intrinsic mechanism plays a crucial role in the AHE,leading to an enhanced anomalous Hall conductivity(AHC)compared with the other rare-earth RMn_(6)Sn_(6)*** band structure calculation reveals a strong hybridization between the 4f electrons of Yb and conduction electrons.

关键词： anomalous Hall effect kagome magnet intermediate valence

Fragility crossover mediated by covalent-like electronic interactions in metallic liquids

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Materials Futures

Materials Futures 2024年第2期3卷 117-130页

作者： Hui-Ru Zhang Liang Gao Yu-Hao Ye Jia-Xin Zhang Tao Zhang Qing-Zhou Bu Qun Yang Zeng-Wei Zhu Shuai Wei Hai-Bin Yu wuhan national high magnetic field center and School of Physics Huazhong University of Science and TechnologyWuhan 430074People’s Republic of China Department of Chemistry Aarhus University8000 AarhusDenmark iMAT Centre for Integrated Materials Research Aarhus University8000 AarhusDenmark

Fragility is one of the central concepts in glass and liquid sciences,as it characterizes the extent of deviation of viscosity from Arrhenius behavior and is linked to a range of glass ***,the intervention of crystallization often prevents the assessment of fragility in poor glass-formers,such as supercooled metallic *** experimental data on their compositional dependence are scarce,let alone fundamentally *** this work,we use fast scanning calorimetry to overcome this obstacle and systematically study the fragility in a ternary La–Ni–Al system,over previously inaccessible composition *** observe fragility dropped in a small range with the Al alloying,indicating an alloying-induced fragility *** use x-ray photoelectron spectroscopy,resistance measurements,electronic structure calculations,and DFT-based deep-learning atomic simulations to investigate the cause of this fragility *** results show that the fragility crossover can be fundamentally ascribed to the electronic covalency associated with the unique Al–Al *** findings provide insight into the origin of fragility in metallic liquids from an electronic structure perspective and pave a new way for the design of metallic glasses.

关键词： metallic glass fragility fast scanning calorimetry density functional theory deep learning potential

Hole mobility enhancement in monolayer WSep-type transistors through molecular doping

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Science China(Information Sciences) 2024年

作者： Shiyuan LIU Xiong XIONG Xin WANG Xinhang SHI Ru HUANG Yanqing WU wuhan national high magnetic field center and School of Integrated Circuits Huazhong University of Science and Technology School of Integrated Circuits and Beijing Advanced Innovation center for Integrated Circuits Peking University

Two-dimensional(2D) transition metal dichalcogenide(TMDC) semiconductor materials exhibit extraordinary electrical properties, holding promise for the realization of next-generation complementary metal-oxide-semiconductor(CMOS) devices at ultimate scaling. However, constrained by effective device doping strategies, the hole mobility and device performance of tungsten diselenide(WSe2) p-type transistors,especially monolayer chemical vapor deposition(CVD)-grown WSe2, have not met expectations. In this paper, an effective performance enhancement of monolayer WSe2p-type transistor was achieved through a molecular doping strategy. Synthesizing monolayer WSe2directly on SiO2back-gated substrates and leveraging energy band alignment design, 4-nitrobenzenediazonium tetrafluoroborate(4-NBD) molecular dopant with a concentration of 10 mM was utilized to modulate the Fermi level position of monolayer WSe2for hole doping. The devices demonstrated a more than 98% increase in hole mobility, reaching up to97 cm2·V-1·s-1while maintaining the current on/off ratio of 108. Monolayer p-type WSe2transistors with 1 μm channel length exhibit a high drive current surpassing 176 μA· μm-1, exceeding previous CVDWSe2devices with similar channel length. This straightforward and effective approach to improving the electrical performance of WSe2transistors paves the way for advanced logic technologies based on transition metal dichalcogenide semiconductors.

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Screening-current-induced magnetic fields and strains in a compact REBCO coil in self field and background field

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Superconductivity 2024年第1期9卷 35-49页

作者： Yufan Yan Donghui Jiang Peng Song Jeonghwan Park Seungyong Hahn Yunfei Tan Timing Qu Department of Electrical and Computer Engineering Seoul National UniversitySeoul 08826Republic of Korea State Key Laboratory of Clean and Efficient Turbomachinery Power Equipment Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China high magnetic field Laboratory Hefei Institutes of Physical ScienceChinese Academy of SciencesHefei 230031China wuhan national high magnetic field center Huazhong University of Science and TechnologyWuhan 430074China

REBa_(2)Cu_(3)O_(7−x)(REBCO)coated conductors,owing to its high tensile strength and current‐carrying ability in a background field,are widely regarded a promising candidate in high‐field *** the great potentials,recent studies have highlighted the challenges posed by screening currents,which are featured by a highly nonuniform current distribution in the superconducting *** this paper,we report a comprehensive study on the behaviors of screening currents in a compact REBCO coil,specifically the screeningcurrent‐induced magnetic fields and *** were carried out in the self‐generated magnetic field and a background field,*** the self‐field condition,the full hysteresis of the magnetic field was obtained by applying current sweeps with repeatedly reversed polarity,as the nominal center field reached 9.17 T with a maximum peak current of 350 *** a background field of 23.15 T,the insert coil generated a center field of 4.17 T with an applied current of 170 ***,a total center field of 32.58 T was achieved before *** the sequential model and the coupled model considering the perpendicular field modification due to conductor deformation are *** comparative study shows that,for this coil,the electromagnetic–mechanical coupling plays a trivial role in self‐field conditions up to 9 *** contrast,with a high axial field dominated by the background field,the coupling effect has a stronger influence on the predicted current and strain *** discussions regarding the role of background field on the strains in the insert suggest potential design strategies to maximize the total center field.

关键词： Electromagnetic-mechanical analysis high‐field insert coil REBCO coated conductor Screening‐current‐induced magnetic field Screening‐current‐induced stress