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arXiv 2024年

作者： Bordoloi, Arjyama Singh, Sobhit Department of Mechanical Engineering University of Rochester RochesterNY14627 United States Materials Science Program University of Rochester RochesterNY14627 United States

Rashba spin-orbit coupling (RSOC) facilitates spin manipulation without relying on an external magnetic field, opening up exciting possibilities for advanced spintronic devices. In this work, we examine the effects of crystal momentum (k) nonlinearity and anisotropy on the conventional Rashba effect, with a particular focus on their impact on the spin Hall conductivity (SHC) in a newly predicted family of 2D Janus materials, W2COX (X = S, Se, Te). Using first-principles density functional theory calculations, we confirm the dynamical and mechanical stability of the studied 2D materials. Strikingly, this materials family exhibits pronounced nonlinear Rashba spin splitting at the Γ point of Brillouin zone near the Fermi level, which cannot be adequately described by the linear-k Rashba model. Therefore, third-order momentum contributions (k3) must be incorporated into the Rashba Hamiltonian. Our analysis reveals that among the studied systems, W2COS exhibits the highest k3 contribution of −45.9 eV Å3, despite having the lowest linear Rashba constant. A detailed analysis of electronic structure reveals topological nontrivial behaviour in these 2D materials, yielding sizable SHC that is primarily governed by the nonlinear Rashba effect. Notably, these materials also exhibit large spin Hall angle (0.018-2.5), which is comparable to that of in bulk topological insulators like Bi2Se3 and Bi2Te3, and surpassing those in narrow bandgap bulk semiconductors GeTe and SnTe, as well as heavy metals such as Pt. Sizable SHC, large spin Hall angles, and the ability to tune SHC via electric fields without altering the topological properties, rooted in the crystal field splitting, underscore the potential of these materials for spintronic applications. © 2024, CC BY.

关键词： Spin Hall effect

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A mini review on two-dimensional nanomaterial assembly

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Nano Research 2020年第5期13卷 1179-1190页

作者： Zhiwei Fang Qiyu Xing Desiree Fernandez Xiao Zhang Guihua Yu Materials Science and Engineering Program and Department of Mechanical Engineering The University of Texas at AustinAustinTexas 78712USA 2 School of Chemistry and Materials ScienceUniversity of Science&Technology of ChinaHefei 230026China

Two-dimensional(2D)nanomaterials have attracted a great deal of attention since the discovery of graphene in 2004,due to their intriguing physicochemical properties and wide-ranging applications in catalysis,energy-related devices,electronics and *** maximize the potential of 2D nanomaterials for their technological applications,controlled assembly of 2D nanobulding blocks into integrated systems is critically *** mini review summarizes the reported strategies of 2D materials-based assembly into integrated functional nanostructures,from in-situ assembly method to post-synthesis *** applications of 2D assembled integrated structures are also covered,especially in the areas of energy,electronics and sensing,and we conclude with discussion on the remaining challenges and potential directions in this emerging field.

关键词： two-dimensional materials assembly self-assembly post-synthesis assembly integrated nanostructures

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Optothermal Manipulation at Fluid Interfaces

Optothermal Manipulation at Fluid Interfaces

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Conference on Lasers and Electro-Optics (CLEO)

作者： Youngsun Kim Carolina Ponce Zhihan Chen Yuebing Zheng Materials Science & Engineering Program Texas Materials Institute The University of Texas at Austin Austin TX USA Walker Department of Mechanical Engineering The University of Texas at Austin Austin TX USA

Optothermal manipulation of particles at fluid interfaces was studied with a film of gold nanoparticles assembled at aqueous/oil interfaces. The unique optothermal behaviors of particles and fluid interfaces under opt... 详细信息

ISBN: (纸本)9781957171258

关键词： Gold Laser beams Laser irradiation Light scattering Optical force Optical tweezers

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First-principles investigation of elastic, vibrational, and thermodynamic properties of kagome metals CsM3Te5 (M = Ti, Zr, Hf)

arXiv

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arXiv 2024年

作者： Wei, Yifan Bordoloi, Arjyama Chuang, Chaon-En Singh, Sobhit Department of Mechanical Engineering University of Rochester RochesterNY14627 United States Materials Science Program University of Rochester RochesterNY14627 United States

Kagome metals are a unique class of quantum materials characterized by their distinct atomic lattice arrangement, featuring interlocking triangles and expansive hexagonal voids. These lattice structures impart exotic properties, including superconductivity, interaction-driven topological many-body phenomena, and magnetism, among others. The kagome metal CsM3Te5 (where M = Ti, Zr, or Hf) exhibits both superconductivity and nontrivial topological electronic properties, offering a promising platform for exploring topological superconductivity. This study employs first-principles density functional theory calculations to systematically analyze the elastic, mechanical, vibrational, thermodynamic, and electronic properties of CsM3Te5 (M = Ti, Zr, Hf). Our calculations reveal that the studied compounds - CsTi3Te5, CsZr3Te5, and CsHf3Te5 - are ductile metals with elastic properties akin to the hexagonal Bi and Sb, with average elastic constants, including a bulk modulus of 27 GPa, a shear modulus of 11 GPa, and Young's modulus of 29 GPa. We observe peculiar dispersionless, flat, phonon branches in the vibrational spectra of these metals. Additionally, we thoroughly analyze the symmetries of the zone-center phonon eigenvectors and predict vibrational fingerprints of the Raman- and infrared-active phonon modes. The analysis of thermodynamic properties reveals the Einstein temperature for CsTi3Te5, CsZr3Te5, and CsHf3Te5 to be 66, 54, and 53 K, respectively. Our orbital-decomposed electronic structure calculations reveal significant in-plane steric interactions and multiple Dirac band crossings near the Fermi level. We further investigate the role of spin-orbit coupling effect on the studied properties. This theoretical investigation sheds light on the intriguing quantum behaviour of kagome metals. © 2024, CC BY.

关键词： Spin orbit coupling

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Electrochemically Modulated Metasurfaces

Electrochemically Modulated Metasurfaces

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Conference on Lasers and Electro-Optics (CLEO)

作者： Janna Eaves-Rathert Elena Kovalik Chibuzor Fabian Ugwu Cary L. Pint Jason G. Valentine Department of Mechanical Engineering Vanderbilt University Nashville TN USA Interdisciplinary Materials Science Program Vanderbilt University Nashville TN USA Department of Mechanical Engineering Iowa State University Ames IA

Electrochemical intercalation of lithium in titanium dioxide and silicon-based metasurfaces is used to initiate phase changes in a continuously tunable, reversible, and bi-stable manner for dynamic control over struct... 详细信息

ISBN: (纸本)9781957171258

关键词： Absorption coefficient Structural color Surface plasmon polaritons Surface plasmons Thin films Titanium dioxide

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Vortex Formation of Active Particles within a Confined Geometry by Velocity Alignment

Vortex Formation of Active Particles within a Confined Geome...

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Conference on Lasers and Electro-Optics (CLEO)

作者： Zhihan Chen Hongru Ding Yuebing Zheng Materials Science & Engineering Program and Texas Materials Institute The University of Texas at Austin Austin TX USA Walker Department of Mechanical Engineering The University of Texas at Austin Austin TX USA

we have developed an optical feedback control system with synchronous control of active particles to study collective motion in nature. Fish-like vortex is observed within a circular confined geometry based on the par... 详细信息

ISBN: (纸本)9781957171258

关键词： Coherence Light fields Optical feedback Polarization Rubidium Spatial light modulators

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Solute Clustering in Polycrystals: Unveiling the Interplay of Grain Boundary Junction and Long-Range Solute Attraction Effects

SSRN

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SSRN 2024年

作者： Nenninger, Tara Sansoz, Frederic Department of Mechanical Engineering The University of Vermont BurlingtonVT05405 United States Materials Science Program The University of Vermont BurlingtonVT05405 United States

Spectral analysis of local atomic environments has become a powerful tool for studying solute atom segregation and interactions at grain boundaries in nanocrystalline alloys. When applied to individual grain boundaries, the spectral analysis has shown that solute-solute interaction can be either attractive or repulsive, with long-range relative attraction enhancing the likelihood for solute cluster nucleation. In this article, we combine this analysis with a new grain-boundary structure descriptor based on grain-boundary atom coordination, to investigate the impact of grain-boundary junctions on solute atom segregation in polycrystals. Specifically, we systematically characterize the nucleation tendency of solute clusters at various types of ordinary grain boundaries, triple junctions, and high-order junctions in Ag polycrystals containing either Ni or Cu solute atoms. Our findings demonstrate that the nucleation of solute clusters at grain boundaries is primarily driven by long-range relative solute attraction, rather than short-range solute-solute interactions. This effect is most pronounced near grain-boundary junctions. Our study highlights the multiscale nature of solute segregation at crystalline interfaces and provides new insights into the complex phenomena governing heterogeneous solute segregation in grain-boundary networks. © 2024, The Authors. All rights reserved.

关键词： Nanocrystalline alloys

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Effect of Parasitic Leakage Currents Associated with the Regrown Aperture of AlGaN/GaN Current Aperture Vertical Electron Transistors (CAVETs)

Effect of Parasitic Leakage Currents Associated with the Reg...

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IEEE Electron Devices Technology and Manufacturing Conference (EDTM)

作者： Sara Pouladi Jae Hyun Ryou Department of Mechanical Engineering Texas Center for Superconductivity at UH Advanced Manufacturing Institute University of Houston USA Department of Electrical and Computer Engineering Materials Science and Engineering Program University of Houston USA

We present a numerical simulation on the effect of leakage paths in the regrown GaN layer in the aperture and above the current blocking layer (CBL) of current aperture vertical electron transistor (CAVET) devices. Here, a 2D TCAD modeling is employed to simulate a CAVET device structure considering two main origins of parasitic leakage current from CBL/regrown-GaN interface and gate/regrown-GaN bulk and their degree of detrimental effect on the characteristics of AlGaN/GaN CAVETs.

关键词： Performance evaluation Apertures Logic gates Numerical simulation Wide band gap semiconductors Numerical models Leakage currents

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Anion order in oxysulfide perovskites:origins and implications

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npj Computational materials 2020年第1期6卷 1062-1072页

作者： Ghanshyam Pilania Ayana Ghosh Steven T.Hartman Rohan Mishra Christopher R.Stanek Blas P.Uberuaga Materials Science and Technology Division Los Alamos National LaboratoryLos AlamosNM 87545USA Materials Science&Engineering University of ConnecticutStorrsCT 06269USA Institute of Materials Science&Engineering and Department of Mechanical Engineering&Materials Science Washington University in St.LouisSt.LouisMO 63130USA

Heteroanionic oxysulfide perovskite compounds represent an emerging class of new materials allowing for a wide range of tunability in the electronic structure that could lead to a diverse spectrum of novel and improved *** cation ordered double perovskites—where the origins and design rules of various experimentally observed cation orderings are well known and understood—anion ordering in heteroanionic perovskites remains a largely uncharted territory.

关键词： perovskite anionic ordered

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Transparent Porphyrin-Based Hybrid Films for Spectral Selective Solar Harvesting and Energy Generation

SSRN

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SSRN 2022年

作者： Shi, Donglu Lin, Jou Wang, Yuxin Lyu, Mengyao Deng, Zicheng The Materials Science and Engineering Program Department of Mechanical Materials Engineering College of Engineering and Applied Science University of Cincinnati CincinnatiOH45221 United States

Spectral-selectively solar harvest is achieved in designated frequency regions for photothermal energy generation. In this study, we have designed and synthesized porphyrin-based hybrids that typically exhibit two absorption peaks respectively near 400 nm (blue-violet) and 700 nm (NIR). To be able to tune the optical absorptions for more efficient solar harvest especially in the IR region, unique porphyrin hybrids are developed by incorporating another porphyrin compound such as phthalocyanine, and inorganic Fe 3 O 4 @Cu 2-x S nanoparticles with different absorption characteristics. By controlling the ratio of the components, the hybrids exhibit gradual and consistent changes in the optical spectra, showing high spectral tunability. Transparent thin films of the hybrids are deposited on glass substrates and constructed in parallel for 3D solar harvesting in a cuboid photothermal generator. Solar light is able to pass through the multilayers of thin films, generating significant thermal heat on each one for enhanced energy density. The structural features of the hybrids are well correlated to the optical behaviors based on Raman studies. Also discussed is the operating mechanisms underlying the photothermal behaviors associated with the hybrid structures. © 2022, The Authors. All rights reserved.

关键词： Multilayers

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