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111.
Modulation of Metal and Insulator States in 2D Ferromagnetic VS2 by van der Waals Interaction Engineering
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Yuqiao Guo Haitao Deng Xu Sun Xiuling Li Jiyin Zhao Junchi Wu Wangsheng Chu Sijia Zhang Haibin Pan Xusheng Zheng Xiaojun Wu Changqing Jin Changzheng Wu Yi Xie 《Advanced materials (Deerfield Beach, Fla.)》2017,29(29)
2D transition‐metal dichalcogenides (TMDCs) are currently the key to the development of nanoelectronics. However, TMDCs are predominantly nonmagnetic, greatly hindering the advancement of their spintronic applications. Here, an experimental realization of intrinsic magnetic ordering in a pristine TMDC lattice is reported, bringing a new class of ferromagnetic semiconductors among TMDCs. Through van der Waals (vdW) interaction engineering of 2D vanadium disulfide (VS2), dual regulation of spin properties and bandgap brings about intrinsic ferromagnetism along with a small bandgap, unravelling the decisive role of vdW gaps in determining the electronic states in 2D VS2. An overall control of the electronic states of VS2 is also demonstrated: bond‐enlarging triggering a metal‐to‐semiconductor electronic transition and bond‐compression inducing metallization in 2D VS2. The pristine VS2 lattice thus provides a new platform for precise manipulation of both charge and spin degrees of freedom in 2D TMDCs availing spintronic applications. 相似文献
112.
Wenhao Huang Feng Wang Lei Yin Ruiqing Cheng Zhenxing Wang Marshet Getaye Sendeku Junjun Wang Ningning Li Yuyu Yao Jun He 《Advanced materials (Deerfield Beach, Fla.)》2020,32(14):1908040
Ferroelectric field-effect transistors (FeFETs) are one of the most interesting ferroelectric devices; however, they, usually suffer from low interface quality. The recently discovered 2D layered ferroelectric materials, combining with the advantages of van der Waals heterostructures (vdWHs), may be promising to fabricate high-quality FeFETs with atomically thin thickness. Here, dual-gated 2D ferroelectric vdWHs are constructed using MoS2, hexagonal boron nitride (h-BN), and CuInP2S6 (CIPS), which act as a high-performance nonvolatile memory and programmable rectifier. It is first noted that the insertion of h-BN and dual-gated coupling device configuration can significantly stabilize and effectively polarize ferroelectric CIPS. Through this design, the device shows a record-high performance with a large memory window, large on/off ratio (107), ultralow programming state current (10−13 A), and long-time endurance (104 s) as nonvolatile memory. As for programmable rectifier, a wide range of gate-tunable rectification behavior is observed. Moreover, the device exhibits a large rectification ratio (3 × 105) with stable retention under the programming state. This demonstrates the promising potential of ferroelectric vdWHs for new multifunctional ferroelectric devices. 相似文献
113.
Michele Serri Giuseppe Cucinotta Lorenzo Poggini Giulia Serrano Philippe Sainctavit Judyta Strychalska-Nowak Antonio Politano Francesco Bonaccorso Andrea Caneschi Robert J. Cava Roberta Sessoli Luca Ottaviano Tomasz Klimczuk Vittorio Pellegrini Matteo Mannini 《Advanced materials (Deerfield Beach, Fla.)》2020,32(24):2000566
Magnetic crystals formed by 2D layers interacting by weak van der Waals forces are currently a hot research topic. When these crystals are thinned to nanometric size, they can manifest strikingly different magnetic behavior compared to the bulk form. This can be the result of, for example, quantum electronic confinement effects, the presence of defects, or pinning of the crystallographic structure in metastable phases induced by the exfoliation process. In this work, an investigation of the magnetism of micromechanically cleaved CrCl3 flakes with thickness >10 nm is performed. These flakes are characterized by superconducting quantum interference device magnetometry, surface-sensitive X-ray magnetic circular dichroism, and spatially resolved magnetic force microscopy. The results highlight an enhancement of the CrCl3 antiferromagnetic interlayer interaction that appears to be independent of the flake size when the thickness is tens of nanometers. The estimated exchange field is 9 kOe, representing an increase of ≈900% compared to the one of the bulk crystals. This effect can be attributed to the pinning of the high-temperature monoclinic structure, as recently suggested by polarized Raman spectroscopy investigations in thin (8–35 nm) CrCl3 flakes. 相似文献
114.
Sanat Ghosh Jaykumar Vaidya Sawani Datta Ram Prakash Pandeya Digambar A. Jangade Ruta N. Kulkarni Kalobaran Maiti Arumugam Thamizhavel Mandar M. Deshmukh 《Advanced materials (Deerfield Beach, Fla.)》2020,32(37):2002220
High-temperature superconductors (HTSs) are important for potential applications and for understanding the origin of strong correlations. Bi2Sr2CaCu2O8+δ (BSCCO), a van der Waals material, offers a platform to probe the physics down to a unit-cell. Guiding the flow of electrons by patterning 2DEGS and oxide heterostructures has brought new functionality and access to new science. Similarly, modifying superconductivity in HTS locally, on a small length scale, is of immense interest for superconducting electronics. A route to modify superconductivity locally by depositing metal on the surface is reported here by transport studies on few unit-cell thick BSCCO. Deposition of chromium (Cr) on the surface over a selected area of BSCCO results in insulating behavior of the underlying region. Cr locally depletes oxygen in CuO2 planes and disrupts the superconductivity in the layers below. This technique of modifying superconductivity is suitable for making sub-micrometer superconducting wires and more complex superconducting devices. 相似文献
115.
Yu Wang Cong Wang Shi-Jun Liang Zecheng Ma Kang Xu Xiaowei Liu Lili Zhang Alemayehu S. Admasu Sang-Wook Cheong Lizheng Wang Moyu Chen Zenglin Liu Bin Cheng Wei Ji Feng Miao 《Advanced materials (Deerfield Beach, Fla.)》2020,32(42):2004533
By virtue of the layered structure, van der Waals (vdW) magnets are sensitive to the lattice deformation controlled by the external strain, providing an ideal platform to explore the one-step magnetization reversal that is still conceptual in conventional magnets due to the limited strain-tuning range of the coercive field. In this study, a uniaxial tensile strain is applied to thin flakes of the vdW magnet Fe3GeTe2 (FGT), and a dramatic increase of the coercive field (Hc) by more than 150% with an applied strain of 0.32% is observed. Moreover, the change of the transition temperatures between the different magnetic phases under strain is investigated, and the phase diagram of FGT in the strain–temperature plane is obtained. Comparing the phase diagram with theoretical results, the strain-tunable magnetism is attributed to the sensitive change of magnetic anisotropy energy. Remarkably, strain allows an ultrasensitive magnetization reversal to be achieved, which may promote the development of novel straintronic device applications. 相似文献
116.
Genki Horiguchi Hidehiro Kamiya Pablo García-Triñanes 《Advanced Powder Technology》2021,32(2):283-289
Understanding the adhesiveness of fine particulate materials at high temperatures is important to achieving the stable, economical operation of various industrial systems. In the present research, two types of calcium carbonate (CaCO3) particles having different mean particle sizes (often used as heat carriers in energy systems) were evaluated. The tensile strengths of beds of these materials were determined at various temperatures by tensile strength measurement tester. The adhesiveness was found to increase greatly at 500 °C even without chemical reactions or sintering, and X-ray diffraction analyses showed thermal expansion of the CaCO3 crystals at 500 °C. Pure alumina (Al2O3) and silica (SiO2) microparticles did not exhibit the same pronounced increases in tensile strength or crystal expansion at this same temperature. Because the surface distances between these primary particles were presumably small, it is proposed that van der Waals forces between the particles greatly increased at high temperatures. The addition of Al2O3 nanoparticles to the CaCO3 decreased the tensile strengths of the powder beds both at ambient temperature and at 500 °C. The experimental data confirm that the surface distances between primary particles were increased upon incorporating the nanoparticles, such that the tensile strength decreased during heat treatment. 相似文献
117.
We present a two-dimensional simulation model to explore cake formation in cross-flow filtration. The model uses the lattice Boltzmann method (LBM) for fluid computation and the discrete element method (DEM) for particle computation; they were fully coupled with the smoothed profile method. We verified our model by simulating filtration under different transmembrane pressures. We then investigated the effects of attractive forces and particle concentration on the cake formation mechanism. Generally, as the attractive interaction and particle concentration increased, the particles formed a cake layer with a looser body and rough surface, due to the decrease in the mobility of the particles in contact with the cake surface. It is concluded that the effects of particle concentration are affected by the different conditions of attractive interactions between the particles. 相似文献
118.
119.
S. El‐Khatib A. Y. Shash A. El‐Habak A. H. Elsayed 《Materialwissenschaft und Werkstofftechnik》2019,50(5):588-598
This paper investigates the physical and mechanical properties of copper‐nickel alloy (at 50 wt.%–50 wt.%) and pure copper, mixed with various types of reinforcement materials such as carbon nanotubes (0.5 wt.%–2 wt.%) as nanoparticles, silicon carbide (1 wt.%–4 wt.%) as microparticles. The acquired composite specimens characteristics were estimated such as microstructure, density, electrical and thermal conductivity, hardness, and compression stress properties to determine the suitable reinforcement percentage that has the best physical and mechanical properties with different main matrix material whether copper‐nickel mechanical alloying or pure copper powder. The micron‐sized silicon carbide and nanosized carbon nanotubes were added to improve the mechanical and physical properties of the composite. The electrical and thermal conductivity of pure copper alloy enhanced compared with the copper‐nickel alloy matrix material. The hardness and compression yield stress of both pure copper and copper‐nickel composites have enhancement values and for copper‐nickel base composites hardness and compression yield stress have enhanced with the most positive enhancement values to examined an optimum percentage of reinforcing material. 相似文献
120.
Zhaolong Chen Zhiqiang Liu Tongbo Wei Shenyuan Yang Zhipeng Dou Yunyu Wang Haina Ci Hongliang Chang Yue Qi Jianchang Yan Junxi Wang Yanfeng Zhang Peng Gao Jinmin Li Zhongfan Liu 《Advanced materials (Deerfield Beach, Fla.)》2019,31(23)
The growth of single‐crystal III‐nitride films with a low stress and dislocation density is crucial for the semiconductor industry. In particular, AlN‐derived deep‐ultraviolet light‐emitting diodes (DUV‐LEDs) have important applications in microelectronic technologies and environmental sciences but are still limited by large lattice and thermal mismatches between the epilayer and substrate. Here, the quasi‐van der Waals epitaxial (QvdWE) growth of high‐quality AlN films on graphene/sapphire substrates is reported and their application in high‐performance DUV‐LEDs is demonstrated. Guided by density functional theory calculations, it is found that pyrrolic nitrogen in graphene introduced by a plasma treatment greatly facilitates the AlN nucleation and enables fast growth of a mirror‐smooth single‐crystal film in a very short time of ≈0.5 h (≈50% decrease compared with the conventional process), thus leading to a largely reduced cost. Additionally, graphene effectively releases the biaxial stress (0.11 GPa) and reduces the dislocation density in the epilayer. The as‐fabricated DUV‐LED shows a low turn‐on voltage, good reliability, and high output power. This study may provide a revolutionary technology for the epitaxial growth of AlN films and provide opportunities for scalable applications of graphene films. 相似文献