Jiuxiang Dai

2H-1T′ Mo _x Re_{(1- x )}S₂ lateral heterostructures are grown by a one-step chemical vapor deposition method, and the optoelectronic properties of 2H Mo _x Re_{(1- x )}S₂, 1T′ Mo _x Re_{(1- x )}S₂, and Mo _x Re_{(1- x )}S₂-based heterostructures are thoroughly studied. Under 405 nm laser irradiation, 2H Mo _x Re_{(1- x )}S₂ exhibits a positive photoconductive effect, while 1T′ Mo _x Re_{(1- x )}S₂ shows a negative photoconductive effect. The optoelectronic response characteristics of Mo _x Re_{(1- x )}S₂-based heterostructures can be modulated by gate voltage.

Abstract

Constructing heterostructures and doping are valid ways to improve the optoelectronic properties of transition metal dichalcogenides (TMDs) and optimize the performance of TMDs-based photodetectors. Compared with transfer techniques, chemical vapor deposition (CVD) has higher efficiency in preparing heterostructures. As for the one-step CVD growth of heterostructures, cross-contamination between the two materials may occur during the growth process, which may provide the possibility of one-step simultaneous realization of controllable doping and formation of alloy-based heterostructures by finely tuning the growth dynamics. Here, 2H-1T′ Mo _x Re_{(1- x )}S₂ alloy-to-alloy lateral heterostructures are synthesized through this one-step CVD growth method, utilizing the cross-contamination and different growth temperatures of the two alloys. Due to the doping of a small amount of Re atoms in 2H MoS₂, 2H Mo _x Re_{(1- x )}S₂ has a high response rejection ratio in the solar-blind ultraviolet (SBUV) region and exhibits a positive photoconductive (PPC) effect. While the 1T′ Mo _x Re_{(1- x )}S₂ formed by heavily doping Mo atoms into 1T' ReS₂ will produce a negative photoconductivity (NPC) effect under UV laser irradiation. The optoelectronic property of 2H-1T′ Mo _x Re_{(1- x )}S₂-based heterostructures can be modulated by gate voltage. These findings are expected to expand the functionality of traditional optoelectronic devices and have potential applications in optoelectronic logic devices.

This work demonstrates that Cr₂Ge₂Te₆ preserves the spin-polarized nature in the amorphous phase, but undergoes a magnetic transition to a spin glass state below 20 Kelvin. Ab initio simulations indicate that the presence of angular disorder and bonding distortions weakens the magnetic order in amorphous Cr₂Ge₂Te₆, leading to the coexistence of ferromagnetic and antiferromagnetic couplings.

Abstract

The layered crystal structure of Cr₂Ge₂Te₆ shows ferromagnetic ordering at the two-dimensional limit, which holds promise for spintronic applications. However, external voltage pulses can trigger amorphization of the material in nanoscale electronic devices, and it is unclear whether the loss of structural ordering leads to a change in magnetic properties. Here, it is demonstrated that Cr₂Ge₂Te₆ preserves the spin-polarized nature in the amorphous phase, but undergoes a magnetic transition to a spin glass state below 20 K. Quantum-mechanical computations reveal the microscopic origin of this transition in spin configuration: it is due to strong distortions of the CrTeCr bonds, connecting chromium-centered octahedra, and to the overall increase in disorder upon amorphization. The tunable magnetic properties of Cr₂Ge₂Te₆ can be exploited for multifunctional, magnetic phase-change devices that switch between crystalline and amorphous states.

Due to the conspicuous advantages of excellent mechanical flexibility, good compatibility, and high plasticity, polymer materials have been at the forefront in building high-performance flexible electronic skins (e-skins) where tactile and non-contact sensing complement each other. This article comprehensively reviews the latest progress on polymer materials-enabled e-skins with tactile and non-contact sensing capabilities and their practical applications in human–machine interactions.

Abstract

Recently, polymer materials have been at the forefront of other materials in building high-performance flexible electronic skin (e-skin) devices due to conspicuous advantages including excellent mechanical flexibility, good compatibility, and high plasticity. However, most research works just paid considerable attention and effort to the design, construction, and possible application of e-skins that reproduce the tactile perception of the human skin sensory system. Compared with tactile sensing devices, e-skins that aim to imitate the non-contact sensing features in the sensory system of human skin tend to avoid undesired issues such as bacteria spreading and mechanical wear. To further promote the development of e-skins to the human skin sensory system where tactile perception and non-contact sensing complement each other, significant progress and advances have been achieved in the field of polymer materials enabled e-skins for both tactile perception and non-contact sensing applications. In this review, the latest progress in polymer material-based e-skins with regard to tactile, non-contact sensing capabilities and their practical applications are introduced. The fabrication strategies of polymer materials and their role in building high-performance e-skins for tactile and non-contact sensing are highlighted. Furthermore, we also review the research works that integrated the polymer-based tactile and non-contact e-skins into robots and prostheses, smart gloves, and VR/AR devices and addressed some representative problems to demonstrate their suitability in practical applications in human–machine interactions. Finally, the current challenges in the construction of high-performance tactile and non-contact e-skins are highlighted and promising properties in this direction, by taking advantage of the polymer materials, are outlined.

Light: Science & Applications, Published online: 05 June 2023; doi:10.1038/s41377-023-01182-7

This paper reviews recent advances that have pushed the boundary of far-field chemical microscopy in terms of spatial resolution as well as their applications in biomedical research, material characterization, environmental study, etc.

The dense structure of alternating sawtooth and flat ferroelectric domain walls found in high quality single crystal BiFeO₃ is re-examined. Using electron diffraction, TEM and aberration-corrected STEM shows that all domain walls are of 180° type and propose a 3D model of this complex microstructure. The tail-to-tail sawtooth structure minimises the local charge density of the domain wall.

Abstract

Previous studies of single crystal BiFeO₃ have found a dense domain structure with alternating sawtooth and flat domain walls (DWs). The nature of these domains and their 3D structure has remained elusive to date. Herein, several sections taken at different orientations are used to examine the structure in detail, concentrating here on the sawtooth DWs using diffraction contrast transmission electron microscopy, electron diffraction, and aberration-corrected scanning transmission electron microscopy (STEM). All DWs are found to be 180° type; the flat walls have head-to-head polarity while the sawtooth DWs are tail-to-tail with peaks elongated along the polar [111] axis, formed by neutral (112¯$11\bar{2}$) DW facets and slightly charged facets with orientations close to (32¯1$3\bar{2}1$) and (2¯31$\overline{2}31$). The neutral DW facets are Ising type and very abrupt, while the charged DW facets have mixed Néel/Bloch/Ising character with a chiral nature and a width of about 2 nm.

Nature Communications, Published online: 05 June 2023; doi:10.1038/s41467-023-39021-3

Characterizing diffusing species is increasingly important for revealing nanoscale processes. Here, the authors uncover the potential of fiber-assisted nanoparticle tracking analysis by characterizing nanoparticles as small as 9 nm at record precision levels, reaching fundamental limits.

Light: Science & Applications, Published online: 06 June 2023; doi:10.1038/s41377-023-01187-2

Perovskite sensitized 2D photodiodes

A review on the basic elements and latest applications of materials informatics in perovskites, catalysts, alloys, two-dimensional materials and polymers.

Abstract

As an implementation tool of data intensive scientific research methods, machine learning (ML) can effectively shorten the research and development (R&D) cycle of new materials by half or even more. ML shows great potential in the combination with other scientific research technologies, especially in the processing and classification of large amounts of material data from theoretical calculation and experimental characterization. It is very important to systematically understand the research ideas of material informatics to accelerate the exploration of new materials. Here, we provide a comprehensive introduction to the most commonly used ML modeling methods in material informatics with classic cases. Then, we review the latest progresses of prediction models, which focus on new processing–structure–properties–performance (PSPP) relationships in some popular material systems, such as perovskites, catalysts, alloys, two-dimensional materials, and polymers. In addition, we summarize the recent pioneering researches in innovation of material research technology, such as inverse design, ML interatomic potentials, and microtopography characterization assistance, as new research directions of material informatics. Finally, we comprehensively provide the most significant challenges and outlooks related to the future innovation and development in the field of material informatics. This review provides a critical and concise appraisal for the applications of material informatics, and a systematic and coherent guidance for material scientists to choose modeling methods based on required materials and technologies.

Nature Communications, Published online: 02 June 2023; doi:10.1038/s41467-023-38508-3

Graphene composites can serve both as efficient thermal insulators at low temperatures and thermal conductors at high temperatures. Here, the authors report the evolution of thermal conductivity of composites with graphene fillers from cryogenic to room temperature.

Nature Communications, Published online: 02 June 2023; doi:10.1038/s41467-023-38991-8

Long-range magnetic ordering of two-dimensional crystals can be sensitive to interlayer coupling, enabling the effective control of interlayer magnetism. Here, the authors report the pressure-controlled interlayer magnetic coupling of chromiumpyrazine coordinated magnets.

Nature Communications, Published online: 02 June 2023; doi:10.1038/s41467-023-38877-9

Bilayer graphene (BLG) is promising for optoelectronic applications due to its tunable bandgap, but its large-area growth on Cu substrates is still challenging. Here, the authors demonstrate the fast synthesis of high-coverage meter-scale BLG on commercial Cu foils by introducing CO2 during the growth.

Sustainable Ironmaking

In article number 2300111, Yan Ma, Dierk Raabe, and co-workers provide a novel approach to deploying intermittent renewable energy mediated by ammonia and using it for a disruptive technology transition towards sustainable ironmaking. This approach sheds light on future sustainable ironmaking, which is urgently needed to mitigate the gigantic amount of CO₂ emissions from the steel industry.

Nature Communications, Published online: 03 June 2023; doi:10.1038/s41467-023-38995-4

Chromium tellurides are a particularly promising family of quasi-2D magnetic materials; towards the single van der Waals layer limit, they preserve magnetic ordering, some even above room temperature, and exhibit a variety of intrinsic topological properties. Here, Hang Chi, Yunbo Ou and co-authors demonstrate a strain tunable Berry curvature induced reversal of the anomalous Hall effect in Cr2Te3.

Low thermal conductivity is highly desired in thermal insulation, data storage, thermoelectric, and spintronic devices. Low thermal conductivity is typically achieved in disordered materials. Herein, this study demonstrates intrinsic superior low thermal conductivity in van der Waals ferromagnet Cr₂Si₂Te₆ single crystals. The low thermal conductivity in Cr₂Si₂Te₆ is realized via spin-phonon scattering, which can advance the spintronic device applications.

Abstract

Layered van der Waals (vdW) magnets are prominent playgrounds for developing magnetoelectric, magneto-optic, and spintronic devices. In spintronics, particularly in spincaloritronic applications, low thermal conductivity (κ) is highly desired. Herein, by combining thermal transport measurements with density functional theory calculations, this study demonstrates low κ down to 1 W m⁻¹ K⁻¹ in a typical vdW ferromagnet Cr₂Si₂Te₆. In the paramagnetic state, development of magnetic fluctuations way above T _c = 33 K strongly reduces κ via spin-phonon scattering, leading to low κ ≈ 1 W m⁻¹ K⁻¹ over a wide temperature range, in comparable to that of amorphous silica. In the magnetically ordered state, emergence of resonant magnon-phonon scattering limits κ below ≈2 W m⁻¹ K⁻¹, which will be three times larger if magnetic scatterings are absent. Application of magnetic fields strongly suppresses the spin-phonon scattering, giving rise to large enhancements of κ. This study's calculations well capture these complex behaviors of κ by taking the temperature- and magnetic-field-dependent spin-phonon scattering into account. Realization of low κ, which is easily tunable by magnetic fields in Cr₂Si₂Te₆, may further promote spincaloritronic applications of vdW magnets. This study's theoretical approach may also provide a generic understanding of spin-phonon scattering, which appears to play important roles in various systems.