The exploration of two-dimensional (2D) antiferromagnetic (AFM) materials has shown great promise and interest in tuning the magnetic and electronic properties as well as studying magneto-optical effects. The current work investigates the control of magneto-optical interactions in alloyed MnxZn1-xPS3 lamellar semiconductor single crystals, with the Mn/Zn ratio regulating the coupling strength. Magnetic susceptibility results show a retention of AFM order followed by a decrease in Néel temperatures down to ~ 40% Mn concentration, below which a paramagnetic behavior is observed. Absorption measurements reveal an increase in bandgap energy with higher Zn(II) concentration, and the presence of Mn(II) d-d transition below the absorption edge. DFT+U approach qualitatively explained the origin and the position of the experimentally observed mid band-gap states in pure MnPS3, and corresponding peaks visible in the alloyed systems MnxZn1-xPS3. Accordingly, emission at 1.3 eV in all alloyed compounds results from recombination from a 4T1g Mn(II) excited state to a hybrid p-d state at the valence band. Most significant, temperature-dependent photoluminescence (PL) intensity trends demonstrate strong magneto-optical coupling in compositions with x > 0.65. This study underscores the potential of tailored alloy compositions as a means to control magnetic and optical properties in 2D materials, paving the way for advances in spin-based technologies.
Alloying Controlled Tuning of Interfacial Spin Orbit Interaction and Magnetic Damping in Crystalline FeCo Alloys
Technical University of Munich（慕尼黑工业大学）；University of Regensburg（雷根斯堡大学）；Fudan University（复旦大学）；Munich Center for Quantum Science and Technology (MCQST)（慕尼黑量子科学与技术中心）；Center for Quantum Engineering (ZQE)（量子工程中心）
We have analyzed by means of scanning tunneling microscopy and spectroscopy the atomic and electronic structure of monolayers of 1T-VxPt1-xSe2 alloys grown by molecular beam epitaxy on epitaxial graphene substrates. We have focused on the composition range (0.1<x<0.35) where ferromagnetic behaviour has recently been demonstrated. For low Pt concentration, (x=0.07 and x=0.21), small domains (a few nanometres in diameter) exhibiting the characteristic superstructure of the charge density wave (CDW) state of pristine VSe2 monolayer remain visible on most of the sample surface. Thus alloying prese…
Applying the approximate DFT-1/2 quasiparticle scheme, band structure unfolding, and generalized quasichemical approximation to describe chemical and structural disorder, we investigate the electronic structure of Bi$_{1-x}$Sb$_x$ alloys from first principles. We calculate the important energy levels near the Fermi energy versus the Sb concentration $x$ where the trivial-topological (TT) and semimetal-semiconductor (SMSC) transitions occur. We demonstrate that the energy variation of the relevant states deviates significantly from linear behavior and that the bowings are important to correctly…
Composition-controlled optical fingerprints and anisotropy of self-trapped excitons in double perovskites
Max Planck Institute for the Structure and Dynamics of Matter（马克斯·普朗克物质结构动力学研究所）；Center for Free-Electron Laser Science（自由电子激光科学中心）；Technion - Israel Institute of Technology（以色列理工学院）
Magnetic properties of amorphous Co$_x$Nb$_{100-x}$ alloys produced by mechanical alloying
从元素粉末开始通过机械合金化制备三种非晶Co $_x$ Nb $_{100-x}$合金，Co $_{25}$ Nb $_{75}$、Co $_{57}$ Nb $_{43}$和Co $_{80}$ Nb $_{20}$。用交变梯度磁力仪（AGFM）测定了它们的磁性能，并由磁滞回线得到了它们的剩磁、饱和磁场和矫顽磁场。合金具有相对高的饱和磁场，其随着成分变得富含Co而降低。矫顽力和回复磁化强度在57%at.Co附近达到最佳值，使得{ \em a}-Co $_{57}$ Nb $_{43}$成为三种合金中最硬的磁性材料。进一步添加Co产生软合金。
Alloying is a powerful tool for tuning materials that facilitates the targeted design of desirable properties for a variety of applications. In this work, we provide a comprehensive investigation of the synthetic accessibility and electronic properties of nine alkaline-earth chalcogenide anion alloys (CaS$_{1-x}$O$_x$, CaS$_{1-x}$Se$_x$, CaS$_{1-x}$Te$_x$, SrS$_{1-x}$O$_x$, SrS$_{1-x}$Se$_x$, SrS$_{1-x}$Te$_x$, MgS$_{1- x}$O$_x$, MgS$_{1-x}$Se$_x$, and MgS$_{1-x}$Te$_x$). We show that isostructural alloying within the rock salt structure is favored for all systems except MgS$_{1-x}$Te$_x$, whi…
The Hidden Cost of Alloying: Disorder-Driven Transport Collapse in TMDs
Dipartimento di Fisica Università della Calabria e INFN-gruppo collegato di Cosenza（卡拉布里亚大学物理系及科森扎INFN联合小组）；Instituto Madrileño de Estudios Avanzados, IMDEA Nanociencia（马德里高级研究院，IMDEA纳米科学研究所）；Departamento de Física de la Materia Condensada, Universidad Autónoma de Madrid（马德里自治大学凝聚态物理系）；Instituto de Física de la Materia Condensada IFIMAC, Univ. Autónoma de Madrid（马德里自治大学凝聚态物理研究所IFIMAC）；Walter Schottky Institute, Technical University of Munich（慕尼黑工业大学瓦尔特·肖特基研究所）；Catalan Institute of Nanoscience and Nanotechnology (ICN2),CSIC and BIST（加泰罗尼亚纳米科学与纳米技术研究所（ICN2），西班牙国家研究委员会和巴塞罗那理工大学）
Deploying an analytical atomistic model of the bulk band structure of the IV-VI semiconductors we connect the spin structure of the topological surface state to the crystal field and spin orbit coupling parameters of the bulk material. While the Dirac-Weyl (or equivalently, Rashba) type topological surface state is often assumed universal, we show that the physics of the surface state is strikingly non-universal. To see this explicitly we calculate the RKKY interaction, which may be viewed as a probe of this surface state spin structure, finding its \emph{qualitative form} depends on the value…
The miscibility of Au and Li exhibits a potential application as an adhesion layer and electrode material in secondary batteries. Here, to explore alloying properties, we constructed a neural network potential (NNP) of Au-Li binary systems based on density functional theory (DFT) calculations. To accelerate construction of NNPs, we proposed an efficient and inexpensive method of structural dataset generation. The predictions by the constructed NNP on lattice parameters and phonon properties agree well with those obtained by DFT calculations. We also investigated the mixing energy of Au$_{1-x}$…
Ru Alloying in Ni/Al Reactive Multilayers: Experimental Observations and Molecular Dynamics Simulations
Laboratory for Nanometallurgy, Department of Materials, ETH Zürich（苏黎世联邦理工学院材料系纳米冶金实验室）；Institute of Physics of Materials, The Czech Academy of Sciences（捷克科学院材料物理研究所）；Central European Institute of Technology, Brno University of Technology（布尔诺理工大学中欧技术研究所）
Tailoring of individual single-atom-thick layers in nanolaminated materials offers atomic-level control over material properties. Nonetheless, multielement alloying in individual atomic layers in nanolaminates is largely unexplored. Here, we report a series of inherently nanolaminated V2(A'xSn1-x)C (A'=Fe, Co, Ni and Mn, and combinations thereof, with x=1/3) synthesized by an alloy-guided reaction. The simultaneous occupancy of the four magnetic elements and Sn, the individual single-atom-thick A layers in the compound constitute high-entropy-alloy analogues, two-dimensional in the sense that …
Since AlN has emerged as an important piezoelectric material for a wide variety of applications, efforts have been made to increase its piezoelectric response via alloying with transition metals that can substitute for Al in the wurtzite lattice. Herein, we report density functional theory calculations of structure and properties of the Cr-AlN system for Cr concentrations ranging past the wurtzite-rocksalt transition point. By studying the different contributions to the longitudinal piezoelectric coefficient, we propose that the physical origin of the enhanced piezoelectricity in Cr$_x$Al$_{1-…
Fe-B-Si system is a matrix for synthesis of new functional materials with exceptional magnetic and mechanical properties. Progress in this area is associated with the search for optimal doping conditions. This theoretical and experimental study is aimed to address the influence of Ta alloying on the structure of undercooled (Fe0.75B0.15Si0.1)100-xTax (x=0-2) melts, their undercoolability and the processes of structure formation during solidification. Small concentration of Ta complicates standard ab initio and machine learning investigations. We developed a technique for fast and stable traini…
Alloying effects on the optical properties of Ge$_{1-x}$Si$_x$ nanocrystals from TDDFT and comparison with effective-medium theory
采用含时密度泛函理论，在绝热局域密度近似（TDLDA）下，计算了Ge $_{1-x}$ Si $_x$合金纳米晶的光谱.光谱作为组成$x$的函数平滑地变化。在Ge侧的组成范围内，在吸收边的最低激发几乎是纯Kohn-Sham独立粒子HOMO-LUMO跃迁，而对于更高的Si含量，发现强烈的混合跃迁。然而，吸收的开始，特别是它的combustion依赖性是类似的独立粒子的结果。此外，经典的去极化效应是一个非常强的抑制的吸收强度负责。我们表明，他们可以考虑在一个更简单的方式使用麦克斯韦-加内特经典有效介质理论。发射光谱是通过计算激发态纳米晶体在其弛豫几何形状下的吸收来研究的。结构对斯托克斯位移的贡献约为0.5 eV。发射光谱在独立粒子渡越离子方面的分解与吸收的分解相似。对于发射，在富锗团簇中发现非常弱的跃迁，远低于强吸收起始。
Temperature and composition dependence of the band gaps of Ga$_{1-x}$In$_x$N alloy: a first-principles study based on the virtual crystal approximation
本文采用第一性原理的虚晶近似（VCA）方法研究了Ga $_{1-x}$ In $_x$ N合金的结构、电子和振动性质。用TB 09泛函获得了3.85 eV的带隙弯曲参数。声子态密度随着In含量的增加向低频移动。然而，VCA忽略了无序效应，因此无法描述合金化后声子谱的展宽。本文还研究了GAN、InN及其合金Ga $_{1-x}$ In $_x$ N的电子-声子相互作用对带隙温度依赖性的影响。计算的零点运动重整化和拟合的Varshni参数在整个组成范围内进行了讨论。
Photocatalytic $H_2$ evolution reactions on pristine TiO$_2$ is characterized by low efficiencies due to trapping and recombination of charge carriers, and due to a sluggish kinetics of electron transfer. Noble metal (mainly Pt, Pd, Au) nanoparticles are typically decorated as cocatalyst on the TiO$_2$ surface to reach reasonable photocatalytic yields. However, owing to the high cost of noble metals, alternative metal cocatalysts are being developed. Here we introduce an approach to fabricate an efficient noble metal free photocatalytic platform for $H_2$ evolution based on alloyed NiCu cocata…
Reduced activation ferritic/martensitic (RAFM) steels are structural materials with potential application in Generation-IV fission and fusion reactors. We use density-functional theory to scrutinize the micro-mechanical properties of the main alloy phases of three RAFM steels based on the body-centered cubic FeCrWVMn solid solution. We assess the lattice parameters and elastic properties of ferromagnetic $α$-Fe and Fe$_{91}$Cr$_{9}$, which are the main building blocks of the RAFM steels, and present a detailed analysis of the calculated alloying effects of V, Cr, Mn, and W on the mechanical pr…
The methodology of single crystal growth of metastable $β$-Ti alloy TIMETAL LCB in an optical floating zone furnace is presented in this paper. Chemical compositions of both precursor material and single crystals were checked. It was found that the concentration of base alloying elements did not change significantly during the growth process, while the concentrations of interstitial elements O and N increased. DSC measurement determined that this concentration shift has a slight impact on ongoing phase transformations, as in the single-crystalline material peak associated with $α$ phase precip…
Automated Phase Mapping with AgileFD and its Application to Light Absorber Discovery in the V-Mn-Nb Oxide System
快速构建相图是组合材料科学的核心原则，加速材料发现的努力往往受到解释组合X射线衍射数据集的挑战的阻碍，我们通过开发AgileFD来解决这个问题，AgileFD是一种人工智能算法，可以从X射线衍射图案的组合库中快速绘制相位图。AgileFD通过卷积非负矩阵分解的新扩展对基于合金的峰位移进行建模，这不仅改善了组成相的识别，而且还将其浓度和晶格参数映射为组成的函数。通过将Gibbs相位规则引入算法，在无监督操作的情况下得到有物理意义的相位图，并通过注入系统的专家知识得到更精细的解。该算法是证明通过调查的V-Mn-Nb氧化物系统，其中分解的8个氧化物相，包括两个大量的合金化，提供了第一个相图为这个伪三元系统。该相图能够解释高通量带隙数据，从而发现新的太阳光吸收剂和基于合金的MnV 2 O 6直接允许带隙能量的调谐。AgileFD算法的开源系列可以在广泛的高通量工作流程中实施，以加速材料发现。
Extremely high excitonic $g$-factors in 2D crystals by alloy-induced admixing of band states
University of Warsaw（华沙大学）；Sapienza University of Rome（罗马第一大学）；University of Central Florida（中佛罗里达大学）；Laboratoire National des Champs Magnétiques Intenses, CNRS-UGA-UPS-INSA-EMFL（强磁场国家实验室）
Synthesis and study of alpha-Fe1.4Ga0.6O3: An advanced Ferromagnetic Semiconductor
本文报道了α-Fe_（1.4）Ga_（0.6）O_3化合物的合成及其结构相稳定性和有趣的磁性、介电和光吸收性质。在我们的工作中，Ga掺杂的α-Fe_2 O_3样品很好地稳定在α相（空间群为R3 C的菱形晶体结构）。本发明的Ga掺杂的α-Fe 2 O 3系统的组合物的性质与最近大多数研究的FeGa O 3组合物相比是显著先进的。在室温下，样品是典型的软铁磁体，同时也是直接带隙半导体。介电研究表明，样品的介电损耗较低，在较高频率下交流电导率大幅增强。在可见光范围内的光吸收增强了4%至5%。该组合物已表现出大范围的剪裁室温铁磁矩和光学带隙，通过改变晶粒尺寸和非环境（真空）热处理的机械合金化制备的样品。
One of the most important and complicated problems in modern industry is to obtaining materials with the required chemical composition, structure and mechanical and physical properties. Solving this problem involves great deal of time and expense, and the results obtained might be far from the optimal solution. The areas of the prediction and optimization of the composition and properties of materials obtained in different technological processes are especially promising. Some of the results were obtained from the modeling of the process of the formation of a weld pool, from modeling of weld m…
We measured the local composition and thickness of SiO2-based glass material from diffraction. By using four dimensional scanning transmission electron microscopy (4D-STEM), we obtained diffraction at each scanning point. Comparing the obtained diffraction with simulated diffraction patterns, we try to measure the local composition and thickness. Although this method requires some constraints, this method measured local composition and thickness with 1/10 or less electron dose of EELS.
Geometric information such as the space groups and crystal systems plays an important role in the properties of crystal materials. Prediction of crystal system and space group thus has wide applications in crystal material property estimation and structure prediction. Previous works on experimental X-ray diffraction (XRD) and density functional theory (DFT) based structure determination methods achieved outstanding performance, but they are not applicable for large-scale screening of materials compositions. There are also machine learning models using Magpie descriptors for composition based m…
Discovering the physical requirements for meeting the indefinite permittivity in natural material as well as proposing a new natural hyperbolic media offer a possible route to significantly improve our knowledge and ability to confine and controlling light in optoelectronic devices. We demonstrate the hyperbolicity in a class of materials with hexagonal P6/mmm and P6$_{3}$/mmc layered crystal structures and its physical origin is thoroughly investigated. By utilizing density functional theory and solving the Bethe-Salpeter equation (BSE), we find that the layered crystal structure and symmetry…
