摘要：
How to effectively induce and manipulate ferromagnetism of two-dimensional non-magnetic materials is the key to expand its application in spintronics. Here, we embedded the iron atom in the C 3 N nanoribbons by substituting the C-C bond or C-N bond to induce ferromagnetism. The structure was verified to be stable by calculating the formation energy. By changing the embedding mode and nanoribbons’ edge configuration, we can obtain ferromagnetic metals, half-metals and ferromagnetic semiconductors. In the wider C 3 N nanoribbons, the electron properties are directly related to the substitution position of the iron atom. The devices constructed by half-metallic nanoribbons and C 3 N nanoribbons have a variety of physical effects. The spin filtering efficiency can reach 99%. Our findings open an avenue for C 3 N-based electronic and spintronic devices.
摘要：
The study of the spin-orbit coupling (SOC) effect is an active research field in physics and it is of great interest for materials with large Rashba spin splitting (RSS) in spintronics applications. In this report, based on firstprinciples calculations, we propose the heterostructure of MoS2/Bi2Te3 with giant RSS duo to the lack of spatial inversion symmetry and the intrinsic electric field perpendicular to the heterostructure. Furthermore, it is found that the electronic and RSS can be tuned effectively by layers of MoS2 and Bi2Te3. When the Bi2Te3 thickness is less than 2QL, these MoS2/Bi2Te3 heterojunction systems exhibit semiconductor properties. The magnitude of the RSS in these MoS2/Bi2Te3 heterojunctions changes with the thickness, and the largest band splitting is found in the (MoS2)(1) (Bi2Te3)(2) heterostructure with a Rashba coefficient of similar to 2.5 eV angstrom, which is a very large value among two-dimensional (2D) materials. While the interlayer distance and charge transfer remain stable at about 3.5 angstrom and 0.1 e, respectively. Through layer-projected band structure analysis, it is proven that the electronic states of these quantum well states (QWSs) are mainly contributed by Bi2Te3, while the MoS2 layer only plays an inductive role and does not contribute to the QWSs electrons. In addition, strain only plays a minor role in the Rashba effect in the MoS2/Bi2Te3 heterojunction, which is mainly caused by the breaking of the spatial inversion symmetry. The giant and tunable Rashba-type SOC of the MoS2/Bi2Te3 heterostructure suggests that it is a type of promising materials for spintronic applications.
关键词：
Adsorption and desorption;Doped graphene;Molecular dynamics
摘要：
Two-dimensional materials have promised an important application as gas sensors due to their big surface areas. Although it's conceptually attractive, the real performance may be dramatically altered at finite temperatures. Therefore, to find out the underlying physical mechanism or dynamics at finite temperatures is of importance before any actual application. Here, we find that boron-doped graphene (BG) should be an ideal sensor to detect gas molecules such as NO2. Our results from first-principle molecular dynamics simulations show NO2 molecule can adsorb stably on BG at room temperature. Furthermore, its desorption time from BG is in the level of micro-seconds (ms), which has fully met the standards of industrial applications. The desorption time will be further decreased to the pico-seconds (ps) level at higher temperature, promising an opportunity for BG to detect the NO2 molecule using more accurate and sensitive measuring techniques, for example femtoseconds laser or ter-ahertz pulses.
通讯机构：
[Cao, Liemao] H;Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang 421002, Peoples R China.
关键词：
Graphyne;Negative differential resistance;Spin-filtering and rectification;DFT
摘要：
Similar to pure graphyne, two-dimension carbon nitride graphyne also possesses exceptional properties and potential applications. In this work, by using the density functional theory (DFT) and combining with nonequilibrium Green's function (NEGF), we study the electronic band structures and transport properties of zigzag rhombic N-graphyne nanoribbons (ZrNGYNRs). Our results show that all of the ZrNGYNRs have similar metallic band structures in no magnetic and ferromagnetic configuration, while the transport properties are directly related to the symmetry of the systems. The electron band structure exhibits a distinct spin splitting in the ferromagnetic state. We propose a device by cutting the ZrNGYNRs in the central scattering region. Negative differential resistance, rectification effects, and spin-filtering effects can be observed in this device. This work highlights the outstanding physics of ZrNGYNRs, and suggest that the ZrNGYNRs is a very promising material in the application of nanoelectronics.
通讯机构：
[Xiaohui Deng; Jiayu Dai] C;College of Physics and Electronic Engineering, Hengyang Normal University, Hengyang, Hunan, 421002, China<&wdkj&>Department of Physics, National University of Defense Technology, Changsha, Hunan, 410073, China<&wdkj&>College of Physics and Electronic Engineering, Hengyang Normal University, Hengyang, Hunan, 421002, China<&wdkj&>Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, Anhui, 230026, China
关键词：
Magnetic semiconductor;Curie temperature;Hole doping
摘要：
It is urgently needed to explore new high temperature magnetic semiconductor or improve its Curie temperature through various physical or chemical methods. Here, we report a new two-dimensional (2D) CrOCl monolayer that has a relatively high Curie temperature. More importantly, it can be further enhanced to over room temperature through hole doping. The structure and the modulation method to improve spin order temperature in this paper thus may be applied in spintronics.
通讯机构：
[Jing Zeng] C;College of Physics and Electronic Engineering, Hengyang Normal University, Hengyang, 421002, PR China<&wdkj&>Hunan Provincial Key Laboratory of Intelligent Information Processing and Application, Hengyang, 421002, PR China
关键词：
Magnetic coupling;Engineering;Transport property;Nanographene dimers
摘要：
A generally accepted viewpoint is that molecules with a spin S = 1/2 did not show any magnetic coupling when assembled into molecular dimers. However, a recent experiment successfully synthesizes covalently linked five-membered ring decorated nanographene dimers that are antiferromagnetically coupled with each other [Phys. Rev. Lett. 124 (2020) 147206]. Motivated by this work, we further study the effect of magnetic coupling engineering on spin transport properties in covalently linked nanographene dimers-based molecular devices. Our results show that excellent spin transport properties are strongly dependent on the magnetic coupling strength of the covalently linked five-membered ring decorated nanographenes. A variety of interesting spin transport properties are found, including “inverse Schottky” characteristic, high spin polarization, reverse of spin polarization, and large magnetoresistance. These results indicate that the covalently linked five-membered ring decorated nanographene dimers can be designed as over-current protection devices, and information storage and logic devices by engineering of magnetic coupling. Our works confirm an efficient way for building high-performance carbon-based molecular spintronic devices.
摘要：
Magnetic semiconductors, with semiconductivity and ferromagnetism simultaneously, have promising important applications as storage devices. However, the ordered ferromagnetic state easily suffers from enhanced thermal fluctuation, inducing a very small Curie temperature. Here we have successfully predicted a new 2D small-gap MoS(2)magnetic semiconductor. Instead, almost all of the reported MoS(2)phase was nonmagnetic whether it exhibited semiconducting or metal behavior. Monte Carlo simulations showed that its Curie temperature could approach 130 K and could be further enhanced through applying biaxial tensile strain. The revealed atomic bonding pattern paves a new way to explore novel electronic and magnetic materials.
摘要：
The high-spin-polarized electronic state has been a central concept in applications such as storage materials and magnetic injection sources. In this work, we predicted the existence of a novel 2D CrO(2)lattice, wherein electrons around the Fermi level were indicated to be completely spin-polarized with an ultra-wide energy range. Monte Carlo simulations showed that such an ordered spin state could be maintained to a temperature of 280 K, and further enhanced through strain or hole doping. The predicted structure here inspired us to archive ideal 2D materials as magnetic storage devices or spin injection sources.
关键词：
Bias voltage;Electronic properties;Ising model;Layered semiconductors;Magnetic fields;Magnetic moments;Molybdenum compounds;Nanoribbons;Edge reconstruction;External magnetic field;Finite temperatures;Long range magnetic order;Low dimensional nanostructures;Low-dimensional systems;Reconstruction patterns;Thermal fluctuations;Sulfur compounds
摘要：
Low-dimensional nanostructures are expected to play an important role in spintronics. However, in low-dimensional systems, thermal fluctuations become more significant, which makes long-range magnetic ordering thermodynamically unfavorable. For example, as predicted by the Ising model, 1D magnetic order cannot survive, even at an arbitrary low finite temperature. In this study, utilizing a nanoproximity effect, we design a MoS2 nanoribbon material to stabilize 1D magnetic order without requiring the explicit application of an external magnetic field. The designed MoS2 nanoribbon has a new edge-reconstruction pattern, which is much more stable than previously reported structures. As a novel electronic property, one edge is nonmagnetic but conductive, and the opposite edge contains a magnetic moment in the predicted reconstruction pattern. Therefore, a bias voltage can drive a current along the former edge, which then generates a magnetic field at the opposite edge to stabilize the 1D magnetic order there. This result opens a new avenue to realize the integrated electrical control of magnetism.
期刊：
PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS,2019年256(11):1900185- ISSN：0370-1972
通讯作者：
Tang, Zhen-Kun;Chen, Mingyang
作者机构：
[Luo, Lin-Tao; Deng, Xiao-Hui; Zhang, Deng-Yu; Tang, Zhen-Kun] Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang 421002, Peoples R China.;[Chen, Mingyang] Beijing Computat Sci Res Ctr, Beijing 100193, Peoples R China.
通讯机构：
[Tang, Zhen-Kun] H;[Chen, Mingyang] B;Hengyang Normal Univ, Coll Phys & Elect Engn, Hengyang 421002, Peoples R China.;Beijing Computat Sci Res Ctr, Beijing 100193, Peoples R China.
关键词：
density functional theory;semiconductor photocatalysts;two-dimensional heterostructures
摘要：
<jats:sec><jats:label /><jats:p>Semiconductor photocatalysts have received a lot of attention because of their wide range of applications in solving energy and environmental problems. In this work, the electronic structure and optical properties of two‐dimensional (2D) heterostructures of bismuth oxyhalides (BiOX, X = Cl, Br, I) and transition‐metal oxides (YO<jats:sub>3</jats:sub>, Y = Mo, W) are studied by density functional theory. The results reveal that the 2D BiOX–YO<jats:sub>3</jats:sub> heterostructures are semiconductors with band gaps of 0–1.41 eV. Electronic structure analyses indicate that the valence band maximum (VBM) and conduction band minimum (CBM) of BiOX–YO<jats:sub>3</jats:sub> are spatially separated and reside in the BiOX and YO<jats:sub>3</jats:sub> layers, respectively. The electron effective masses of BiOI–YO<jats:sub>3</jats:sub> (Y = Mo, W) heterostructures, especially BiOI–WO<jats:sub>3</jats:sub>, are significantly lower than those of BiOI and YO<jats:sub>3</jats:sub>. BiOI–YO<jats:sub>3</jats:sub> (Y = Mo, W) heterostructures exhibit a good absorption in the visible light region. The enhanced optoelectronic properties of BiOI–YO<jats:sub>3</jats:sub> are found to be related to the comparably large lattice mismatches between BiOI and YO<jats:sub>3</jats:sub>. The ultra‐low electron effective mass and good visible absorption of the BiOI–WO<jats:sub>3</jats:sub> heterostructure make it a promising candidate for the high‐efficient photocatalyts for water‐splitting.</jats:p></jats:sec>
作者机构：
[Xiaohui Deng; Mingsu Si; Jiayu Dai] Department of Physics and Electronic Information Science,Hengyang Normal University;[Xiaohui Deng; Mingsu Si; Jiayu Dai] Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education,Lanzhou University;[Xiaohui Deng; Mingsu Si; Jiayu Dai] Department of Physics,College of Science,National University of Defense Technology
会议名称：
第九届计算纳米科学与新能源材料国际研讨会
会议时间：
2016-06-22
会议地点：
中国上海
摘要：
<正>Modern electronic technology based on silicon semiconductor is faced with the limit from thermal effect and quantum effect.Therefore,to look for new alternative materials becomes to be an important
作者机构：
[Zeng, Jing; Deng, Xiaohui] Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang 421008, Peoples R China.;[Si, Mingsu] Lanzhou Univ, Minist Educ, Key Lab Magnetism & Magnet Mat, Lanzhou 730000, Peoples R China.;[Lu, Wei] Hong Kong Polytech Univ, Univ Res Facil Mat Characterizat & Device Fabrica, Hong Kong, Hong Kong, Peoples R China.
通讯机构：
[Deng, Xiaohui] H;Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang 421008, Peoples R China.
关键词：
EPL;Europhysics Letters
摘要：
The modulation of the band gap in the two-dimensional carbon materials is of importance for their applications as electronic devices. By first-principles calculations, we propose a model to control the band gap size of <i>γ<i/>-graphyne. The model is named as <i>p<i/>-<i>n<i/> codoping, <i>i.e.<i/>, using B and N atoms to codope into <i>γ<i/>-graphyne. After codoping, the B atom plays the role of <i>p<i/> dopant and the N atom acts as <i>n<i/> dopant. The Fermi energy level returns around the forbidden zone and the band gap of <i>γ<i/>-graphyne becomes bigger or smaller. Moreover, the gaps exhibit an oscillating behaviour in the different codoping configurations. The proposed model serves as new insights for a better modulation of the electronic properties of 2D carbon materials.
作者机构：
[Zeng, Jing; Deng, Xiaohui] Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang 421008, Peoples R China.;[Si, Mingsu] Lanzhou Univ, Minist Educ, Key Lab Magnetism & Magnet Mat, Lanzhou 730000, Peoples R China.;[Lu, Wei] Hong Kong Polytech Univ, Univ Res Facil Mat Characterizat & Device Fabrica, Hong Kong, Hong Kong, Peoples R China.
通讯机构：
[Deng, Xiaohui] H;Hengyang Normal Univ, Dept Phys & Elect Informat Sci, Hengyang 421008, Peoples R China.
摘要：
A theoretical model is presented that reveals the mechanism of spontaneous boron doping of graphene and is consistent with the microwave plasma experiment choosing trimethylboron as the doping source (Tang et al. (2012) [19]). The spontaneous boron doping originates from the synergistic effect of B and other groups (C, H, CH, CH2 or CH3) decomposing from trimethylboron. This work successfully explains the above experimental phenomenon and proposes a novel and feasible method aiming at B doping of graphene. The mechanism presented here may be also suitable for other two-dimensional carbon-based materials. (C) 2016 Elsevier B.V. All rights reserved.
摘要：
A photoswitched single-molecule junction, a stable and reversible single-molecule electrical switch, has been successfully prepared by means of molecular engineering (2016 Science 352 1443). In this work we use a first-principles computational approach to investigate the spin valve effect of an azobenzene-based spin optoelectronic device. Our results demonstrate that the magnetoresistive ratio of the spin optoelectronic device is only about 65% when the azobenzene is in cis configuration, which is a low performance for practical applications. However, the magnetoresistive ratio of the device can be enhanced to about 2775% when the cis configuration of the azobenzene is changed into the trans configuration by applying a pulse of light. As a consequence, photoexcitation provides an effective way to obtain a high-performance spin optoelectronic device.
