共查询到20条相似文献,搜索用时 15 毫秒
1.
Chaolong Tang Zhaowei Zhang Shen Lai Qinghai Tan Wei-bo Gao 《Advanced materials (Deerfield Beach, Fla.)》2020,32(16):1908498
2D van der Waals heterostructures serve as a promising platform to exploit various physical phenomena in a diverse range of novel spintronic device applications. Efficient spin injection is the prerequisite for these devices. The recent discovery of magnetic 2D materials leads to the possibility of fully 2D van der Waals spintronics devices by implementing spin injection through the magnetic proximity effect (MPE). Here, the investigation of MPE in 2D graphene/CrBr3 van der Waals heterostructures is reported, which is probed by the Zeeman spin Hall effect through non-local measurements. Quantitative estimation of the Zeeman splitting field demonstrates a significant MPE field even in a low magnetic field. Furthermore, the observed anomalous longitudinal resistance changes at the Dirac point RXX,D with increasing magnetic field near ν = 0 may be attributed to the MPE-induced new ground state phases. This MPE revealed in the graphene/CrBr3 van der Waals heterostructures therefore provides a solid physics basis and key functionality for next-generation 2D spin logic and memory devices. 相似文献
2.
Louis Donald Notemgnou Mouafo Florian Godel Georgian Melinte Samar Hajjar‐Garreau Hicham Majjad Bruno Dlubak Ovidiu Ersen Bernard Doudin Laurent Simon Pierre Seneor Jean‐Francois Dayen 《Advanced materials (Deerfield Beach, Fla.)》2018,30(38)
Fabrication and spintronics properties of 2D–0D heterostructures are reported. Devices based on graphene (“Gr”)–aluminium nanoclusters heterostructures show robust and reproducible single‐electron transport features, in addition to spin‐dependent functionality when using a top magnetic electrode. The magnetic orientation of this single ferromagnetic electrode enables the modulation of the environmental charge experienced by the aluminium nanoclusters. This anisotropic magneto‐Coulomb effect, originating from spin–orbit coupling within the ferromagnetic electrode, provides tunable spin valve‐like magnetoresistance signatures without the requirement of spin coherent charge tunneling. These results extend the capability of Gr to act both as electrode and as a platform for the growth of 2D–0D mixed‐dimensional van der Waals heterostructures, providing magnetic functionalities in the Coulomb blockade regime on scalable spintronic devices. These heterostructures pave the way towards novel device architectures at the crossroads of 2D material physics and spin electronics. 相似文献
3.
In order to achieve highly efficient spin polarized transport, first of all magnetocrystalline anisotropy energy, which determines the magnetic easy axis, must be understood. The highly precise full-potential linearized augmented plane-wave method is employed to investigate the magnetism and magnetocrystalline anisotropy energy of a ferromagnetic Heusler alloy Fe3Si on Si(001) and Si(111) substrates. The calculated magnetocrystalline anisotropy energy of bulk D03 Fe3Si was found to depend sensitively on a tetragonal distortion: The magnetization is along the z-axis at c/a < 1 and on the xy plane at c/a > 1. The out-of-plane magnetic easy axis of both Fe3Si/Si(001) and (111) was calculated to be quite stable with enhanced magnetocrystalline anisotropy energy compared with bulk value. The magnetic easy axis of Fe3Si/Si(001) and (111) is discussed in detail with single particle energy spectra. The degree of spin polarization is also presented at the interfaces between Fe3Si and Si. The calculated spin polarizations of Fe3Si/Si(111) tend to retain the spin polarization of the bulk, whereas they are reduced for the (001) interfaces. 相似文献
4.
Nakanishi Yudai Ishi Ayumi Ohata Chika Soriano David Iwaki Ryo Nomura Kyoko Hasegawa Miki Nakamura Taketomo Katsumoto Shingo Roche Stephan Haruyama Junji 《Nano Research》2017,10(2):718-728
The formation and control of a room-temperature magnetic order in twodimensional (2D) materials is a challenging quest for the advent of innovative magnetic-and spintronic-based technologies.To date,edge magnetism in 2D materials has been experimentally observed in hydrogen (H)-terminated graphene nanoribbons (GNRs) and graphene nanomeshes (GNMs),but the measured magnetization remains far too small to allow envisioning practical applications.Herein,we report experimental evidences of large room-temperature edge ferromagnetism (FM) obtained from oxygen (O)-terminated zigzag pore edges of few-layer black phosphorus (P) nanomeshes (BPNMs).The magnetization values per unit area are ~100 times larger than those reported for H-terminated GNMs,while the magnetism is absent for H-terminated BPNMs.The magnetization measurements and the first-principles simulations suggest that the origin of such a magnetic order could stem from ferromagnetic spin coupling between edge P with O atoms,resulting in a strong spin localization at the edge valence band,and from uniform oxidation of full pore edges over a large area and interlayer spin interaction.Our findings pave the way for realizing high-efficiency 2D flexible magnetic and spintronic devices without the use of rare magnetic elements. 相似文献
5.
Si(001)-c(4×4) surfaces are obtained by exposing Si(001)-2×1 surfaces at 600°C to ethylene doses that determine C coverages in the submonolayer range. This reconstruction reveals a carbon enrichment of the topmost silicon layers. As the c(4×4) reflection high energy electron diffraction pattern can be maintained in spite of rather thick Si regrowth layers, we can conclude that this C derm is able to float at the surface during the Si capping. This segregation process is strongly dependent on the growth mode. As identified by RHEED intensity oscillations, a Si step flow growth is necessary to allow carbon to float in the first four silicon top-layers. An interplay is found between the kinetic growth conditions leading to this C-segregation and those of a self-organization process of C-rich clusters that we have observed in the course of Si1−yCy alloy growth obtained by codeposition of silicon and carbon. 相似文献
6.
Songtian Li Konstantin V. Larionov Zakhar I. Popov Takahiro Watanabe Kenta Amemiya Shiro Entani Pavel V. Avramov Yuya Sakuraba Hiroshi Naramoto Pavel B. Sorokin Seiji Sakai 《Advanced materials (Deerfield Beach, Fla.)》2020,32(6):1905734
Graphene-based vertical spin valves (SVs) are expected to offer a large magnetoresistance effect without impairing the electrical conductivity, which can pave the way for the next generation of high-speed and low-power-consumption storage and memory technologies. However, the graphene-based vertical SV has failed to prove its competence due to the lack of a graphene/ferromagnet heterostructure, which can provide highly efficient spin transport. Herein, the synthesis and spin-dependent electronic properties of a novel heterostructure consisting of single-layer graphene (SLG) and a half-metallic Co2Fe(Ge0.5Ga0.5) (CFGG) Heusler alloy ferromagnet are reported. The growth of high-quality SLG with complete coverage by ultrahigh-vacuum chemical vapor deposition on a magnetron-sputtered single-crystalline CFGG thin film is demonstrated. The quasi-free-standing nature of SLG and robust magnetism of CFGG at the SLG/CFGG interface are revealed through depth-resolved X-ray magnetic circular dichroism spectroscopy. Density functional theory (DFT) calculation results indicate that the inherent electronic properties of SLG and CFGG such as the linear Dirac band and half-metallic band structure are preserved in the vicinity of the interface. These exciting findings suggest that the SLG/CFGG heterostructure possesses distinctive advantages over other reported graphene/ferromagnet heterostructures, for realizing effective transport of highly spin-polarized electrons in graphene-based vertical SV and other advanced spintronic devices. 相似文献
7.
We report the formation of PtSi nanowires, PtSi/Si/PtSi nanowire heterostructures, and nanodevices from such heterostructures. Scanning electron microscopy studies show that silicon nanowires can be converted into PtSi nanowires through controlled reactions between lithographically defined platinum pads and silicon nanowires. High-resolution transmission electron microscopy studies show that PtSi/Si/PtSi heterostructure has an atomically sharp interface with epitaxial relationships of Si[110]//PtSi[010] and Si(111)//PtSi(101). Electrical measurements show that the pure PtSi nanowires have low resistivities approximately 28.6 microOmega.cm and high breakdown current densities>1x10(8) A/cm2. Furthermore, using single crystal PtSi/Si/PtSi nanowire heterostructures with atomically sharp interfaces, we have fabricated high-performance nanoscale field-effect transistors from intrinsic silicon nanowires, in which the source and drain contacts are defined by the metallic PtSi nanowire regions, and the gate length is defined by the Si nanowire region. Electrical measurements show nearly perfect p-channel enhancement mode transistor behavior with a normalized transconductance of 0.3 mS/microm, field-effect hole mobility of 168 cm2/V.s, and on/off ratio>10(7), demonstrating the best performing device from intrinsic silicon nanowires. 相似文献
8.
《Current Opinion in Solid State & Materials Science》2016,20(6):388-395
Two-dimensional (2D) systems have considerably strengthened their position as one of the premier candidates to become the key material for the proposed spintronics technology, in which computational logic, communications and information storage are all processed by the electron spin. In this article, some of the most representative 2D materials including ferromagnetic metals (FMs) and diluted magnetic semiconductor (DMSs) in their thin film form, magnetic topological insulators (TIs), magnetic graphene and magnetic transition metal dichalcogenides (TMDs) are reviewed for their recent research progresses. FM thin films have spontaneous magnetization and usually high Curie temperature (Tc), though this can be strongly altered when bonded with semiconductors (SCs). DMS and magnetic TIs have the advantage of easy integration with the existing SC-based technologies, but less robust magnetism. Magnetic ordering in graphene and TMDs are even more fragile and limited to cryogenic temperatures so far, but they are particularly interesting topics due to the desired long spin lifetime as well as the outstanding mechanical and optical properties of these materials. 相似文献
9.
2D van der Waals (vdW) magnets, which present intrinsic ferromagnetic/antiferromagnetic ground states at finite temperatures down to atomic‐layer thicknesses, open a new horizon in materials science and enable the potential development of new spin‐related applications. The layered structure of vdW magnets facilitates their atomic‐layer cleavability and magnetic anisotropy, which counteracts spin fluctuations, thereby providing an ideal platform for theoretically and experimentally exploring magnetic phase transitions in the 2D limit. With reduced dimensions, the susceptibility of 2D magnets to a large variety of external stimuli also makes them more promising than their bulk counterpart in various device applications. Here, the current status of characterization and tuning of the magnetic properties of 2D vdW magnets, particularly the atomic‐layer thickness, is presented. Various state‐of‐the‐art optical and electrical techniques have been applied to reveal the magnetic states of 2D vdW magnets. Other emerging 2D vdW magnets and future perspectives on the stacking strategy are also given; it is believed that they will excite more intensive research and provide unprecedented opportunities in the field of spintronics. 相似文献
10.
The possibility to graft nano-objects directly on its surface makes graphene particularly appealing for device and sensing applications. Here we report the design and the realization of a novel device made by a graphene nanoconstriction decorated with TbPc(2) magnetic molecules (Pc = phthalocyananine), to electrically detect the magnetization reversal of the molecules in proximity with graphene. A magnetoconductivity signal as high as 20% is found for the spin reversal, revealing the uniaxial magnetic anisotropy of the TbPc(2) quantum magnets. These results depict the behavior of multiple-field-effect nanotransistors with sensitivity at the single-molecule level. 相似文献
11.
Bru-Chevallier C El Akra A Pelloux-Gervais D Dumont H Canut B Chauvin N Regreny P Gendry M Patriarche G Jancu JM Even J Noe P Calvo V Salem B 《Journal of nanoscience and nanotechnology》2011,11(10):9153-9159
The aim of this study is to achieve homogeneous, high density and dislocation free InGaAs quantum dots grown by molecular beam epitaxy for light emission on silicon substrates. This work is part of a project which aims at overcoming the severe limitation suffered by silicon regarding its optoelectronic applications, especially efficient light emission device. For this study, one of the key points is to overcome the expected type II InGaAs/Si interface by inserting the InGaAs quantum dots inside a thin silicon quantum well in SiO2 fabricated on a SOI substrate. Confinement effects of the Si/SiO2 quantum well are expected to heighten the indirect silicon bandgap and then give rise to a type I interface with the InGaAs quantum dots. Band structure and optical properties are modeled within the tight binding approximation: direct energy bandgap is demonstrated in SiO2/Si/InAs/Si/SiO2 heterostructures for very thin Si layers and absorption coefficient is calculated. Thinned SOI substrates are successfully prepared using successive etching process resulting in a 2 nm-thick Si layer on top of silica. Another key point to get light emission from InGaAs quantum dots is to avoid any dislocations or defects in the quantum dots. We investigate the quantum dot size distribution, density and structural quality at different V/III beam equivalent pressure ratios, different growth temperatures and as a function of the amount of deposited material. This study was performed for InGaAs quantum dots grown on Si(001) substrates. The capping of InGaAs quantum dots by a silicon epilayer is performed in order to get efficient photoluminescence emission from quantum dots. Scanning transmission electronic microscopy images are used to study the structural quality of the quantum dots. Dislocation free In50Ga50As QDs are successfully obtained on a (001) silicon substrate. The analysis of QDs capped with silicon by Rutherford Backscattering Spectrometry in a channeling geometry is also presented. 相似文献
12.
We demonstrated that graphene significantly enhances the reversible capacity of porous silicon nanowires used as the anode in Li-ion batteries. We prepared our experimental nanomaterials, viz., graphene and porous single-crystalline silicon nanowires, respectively, using a liquid-phase graphite exfoliation method and an electroless HF/AgNO3 etching process. The Si porous nanowire/graphene electrode realized a charge capacity of 2470 mAh g(-1) that is much higher than the 1256 mAh g(-1) of porous Si nanowire/C-black electrode and 6.6 times the theoretical capacity of commercial graphite. This relatively high capacity could originate from the favorable charge-transportation characteristics of the combination of graphene with the porous Si 1D nanostructure. 相似文献
13.
Jihyung Seo Junghyun Lee Gyujeong Jeong Hyesung Park 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(2)
The surface property of growth substrate imposes significant influence in the growth behaviors of 2D materials. Rhenium disulfide (ReS2) is a new family of 2D transition metal dichalcogenides with unique distorted 1T crystal structure and thickness‐independent direct bandgap. The role of growth substrate is more critical for ReS2 owing to its weak interlayer coupling property, which leads to preferred growth along the out‐of‐plane direction while suppressing the uniform in‐plane growth. Herein, graphene is introduced as the growth substrate for ReS2 and the synthesis of graphene/ReS2 vertical heterostructure is demonstrated via chemical vapor deposition. Compared with the rough surface of SiO2/Si substrate with dangling bonds which hinders the uniform growth of ReS2, the inert and smooth surface nature of graphene sheet provides a lower energy barrier for migration of the adatoms, thereby promoting the growth of ReS2 on the graphene surface along the in‐plane direction. Furthermore, patterning of the graphene/ReS2 heterostructure is achieved by the selective growth of ReS2, which is attributed to the strong binding energy between sulfur atoms and graphene surface. The fundamental studies in the role of graphene as the growth template in the formation of van der Waals heterostructures provide better insights into the synthesis of 2D heterostructures. 相似文献
14.
Hua Lv Alessandra da Silva Adriana I. Figueroa Charles Guillemard Iván Fernández Aguirre Lorenzo Camosi Lucia Aballe Manuel Valvidares Sergio O. Valenzuela Jürgen Schubert Martin Schmidbauer Jens Herfort Michael Hanke Achim Trampert Roman Engel-Herbert Manfred Ramsteiner Joao Marcelo J. Lopes 《Small (Weinheim an der Bergstrasse, Germany)》2023,19(39):2302387
Van der Waals (vdW) heterostructures combining layered ferromagnets and other 2D crystals are promising building blocks for the realization of ultracompact devices with integrated magnetic, electronic, and optical functionalities. Their implementation in various technologies depends strongly on the development of a bottom-up scalable synthesis approach allowing for realizing highly uniform heterostructures with well-defined interfaces between different 2D-layered materials. It is also required that each material component of the heterostructure remains functional, which ideally includes ferromagnetic order above room temperature for 2D ferromagnets. Here, it is demonstrated that the large-area growth of Fe5−xGeTe2/graphene heterostructures is achieved by vdW epitaxy of Fe5−xGeTe2 on epitaxial graphene. Structural characterization confirms the realization of a continuous vdW heterostructure film with a sharp interface between Fe5−xGeTe2 and graphene. Magnetic and transport studies reveal that the ferromagnetic order persists well above 300 K with a perpendicular magnetic anisotropy. In addition, epitaxial graphene on SiC(0001) continues to exhibit a high electronic quality. These results represent an important advance beyond nonscalable flake exfoliation and stacking methods, thus marking a crucial step toward the implementation of ferromagnetic 2D materials in practical applications. 相似文献
15.
Alexander N. Chaika Olga V. Molodtsova Alexei A. Zakharov Dmitry Marchenko Jaime Sanchez-Barrig Andrei Varykhalov Igor V. Shvets Victor Yu. Aristov 《Nano Research》2013,6(8):562-570
The atomic and electronic structure of graphene synthesized on commercially available cubic-SiC(001)/Si(001) wafers have been studied by low energy electron microscopy (LEEM), scanning tunneling microscopy (STM), low energy electron diffraction (LEED), and angle resolved photoelectron spectroscopy (ARPES). LEEM and STM data prove the wafer-scale continuity and uniform thickness of the graphene overlayer on SIC(001). LEEM, STM and ARPES studies reveal that the graphene overlayer on SIC(001) consists of only a few monolayers with physical properties of quasi-freestanding graphene. Atomically resolved STM and micro-LEED data show that the top graphene layer consists of nanometer-sized domains with four different lattice orientations connected through the 〈110〉-directed boundaries. ARPES studies reveal the typical electron spectrum of graphene with the Dirac points close to the Fermi level. Thus, the use of technologically relevant SiC(001)/Si(001) wafers for graphene fabrication repre-sents a realistic way of bridging the gap between the outstanding properties of graphene and their applications. 相似文献
16.
Minghu Peng Yunbo Zhong Tianxiang Zheng Lijun Fan Junfeng Zhou Weili Ren Zhongming Ren 《材料科学技术学报》2018,34(12):2492-2497
A new preparation method of near-net-shape 6.5?wt% Si high silicon steel sheets was proposed by combining composite electrodeposition (CED) and diffusion annealing under magnetic field. The obtained sheets were characterized by scanning electron microscopy, energy dispersive spectrometry, analytical balance and a silicon steel material measurement system. The results show that the surface morphology, the elemental distribution, the cathode current efficiency and the silicon content of coatings were obviously influenced by the micro and macro magnetohydrodynamics (MHD) flows under magnetic field. With the effect of magnetic field, the silicon particles content of coatings showed an increasing trend and the diffusion process showed that an approximately uniform 6.5?wt% silicon steel sheet has been successfully obtained. The magnetism measurement showed that the high silicon steel sheet has the lower iron loss, and the iron loss further decreased under magnetic field. The new method proposed in this article, which is more environmentally friendly and low energy consumption, is feasible to prepare high silicon steel sheets. 相似文献
17.
Zheng Liu Luiz H. G. Tizei Yohei Sato Yung‐Chang Lin Chao‐Hui Yeh Po‐Wen Chiu Masami Terauchi Sumio Iijima Kazu Suenaga 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(2):252-259
Combinations of 2D materials with different physical properties can form heterostructures with modified electrical, mechanical, magnetic, and optical properties. The direct observation of a lateral heterostructure synthesis is reported by epitaxial in‐plane graphene growth from the step‐edge of hexagonal BN (h‐BN) within a scanning transmission electron microscope chamber. Residual hydrocarbon in the chamber is the carbon source. The growth interface between h‐BN and graphene is atomically identified as largely N–C bonds. This postgrowth method can form graphene nanoribbons connecting two h‐BN domains with different twisting angles, as well as isolated carbon islands with arbitrary shapes embedded in the h‐BN layer. The electronic properties of the vertically stacked h‐BN/graphene heterostructures are investigated by electron energy‐loss spectroscopy (EELS). Low‐loss EELS analysis of the dielectric response suggests a robust coupling effect between the graphene and h‐BN layers. 相似文献
18.
采用基于密度泛函理论的第一性原理研究了4H-SiC(001)定位掺杂Ni的磁性,结果表明相对于掺杂前表面悬挂键的存在使体系具有弱磁性,Ni定位取代Si位置后得到的体系更加稳定。对比分析了Ni定位取代不同数量的C与Si原子后,得出取代C原子比取代Si原子得到的磁矩大,而且奇数倍的取代较偶数倍取代得到的磁矩大。定位取代一个C与一个Si比单独取代一种原子得到的磁矩大,因此从稳定性与磁性方面考虑C与Si同时取代是最好的掺杂选择。在导电性方面,随着Ni掺杂原子数量增加光电导相应增加。 相似文献
19.
Yan‐Fei Wu Liang Zhang Cai‐Zhen Li Zhen‐Sheng Zhang Song Liu Zhi‐Min Liao Dapeng Yu 《Advanced materials (Deerfield Beach, Fla.)》2018,30(34)
Dirac semimetal is an emerging class of quantum matters, ranging from 2D category, such as, graphene and surface states of topological insulator to 3D category, for instance, Cd3As2 and Na3Bi. As 3D Dirac semimetals typically possess Fermi‐arc surface states, the 2D–3D Dirac van der Waals heterostructures should be promising for future electronics. Here, graphene–Cd3As2 heterostructures are fabricated through direct layer‐by‐layer stacking. The electronic coupling results in a notable interlayer charge transfer, which enables us to modulate the Fermi level of graphene through Cd3As2. A planar graphene p–n–p junction is achieved by selective modification, which demonstrates quantized conductance plateaus. Moreover, compared with the bare graphene device, the graphene–Cd3As2 hybrid device presents large nonlocal signals near the Dirac point due to the charge transfer from the spin‐polarized surface states in the adjacent Cd3As2. The results enrich the family of van der Waals heterostructure and should inspire more studies on the application of Dirac/Weyl semimetals in spintronics. 相似文献
20.
We report a general method for determining the spin polarization from nanowire materials using Andreev reflection spectroscopy implemented with a Nb superconducting contact and common electron-beam lithography device fabrication techniques. This method was applied to magnetic semiconducting Fe(1-x)Co(x)Si alloy nanowires with x? = 0.23, and the average spin polarization extracted from 6 nanowire devices is 28 ± 7% with a highest observed value of 35%. Local-electrode atom probe tomography (APT) confirms the homogeneous distribution of Co atoms in the FeSi host lattice, and X-ray magnetic circular dichroism (XMCD) establishes that the elemental origin of magnetism in this strongly correlated electron system is due to Co atoms. 相似文献