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Microstructural analysis and electro-optic properties of thick epitaxial BaTiO3 films integrated on silicon (001)

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Physical Review Materials 2022年第9期6卷 095201-095201页

作者： Marc Reynaud Zuoming Dong Hyoju Park Wente Li Agham B. Posadas Jamie H. Warner Daniel Wasserman Alexander A. Demkov Department of Physics University of Texas at Austin Austin Texas 78712 USA Department of Electrical and Computer Engineering University of Texas at Austin Austin Texas 78758 USA Walker Department of Mechanical Engineering University of Texas at Austin Austin Texas 78712 USA Materials Science and Engineering Program and Texas Materials Institute The University of Texas at Austin Texas 78712 USA

Recent advances in epitaxial oxide deposition have enabled the fabrication of thick films of ferroelectric perovskite BaTiO3 capable of providing a robust electro-optic response via the Pockels effect in silicon photonic devices. We report a microstructure analysis of such films integrated on Si(001) by molecular beam epitaxy, showing how the crystallographic and polarization orientation change as a function of thickness. The measured electro-optic properties of the film correlate well with the microstructural analysis and demonstrate the potential of Si-integrated BaTiO3 for silicon photonics. An effective Pockels coefficient of up to 268 pm/V has been demonstrated in 110-nm-thick films in transmission measurements and 352 pm/V in waveguide measurements.

关键词： Ferroelectricity Photonics Epitaxy

Backscattering-free edge states below all bands in two-dimensional auxetic media

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arXiv 2023年

作者： Cheng, Wenting Qian, Kai Cheng, Nan Boechler, Nicholas Mao, Xiaoming Sun, Kai Department of Physics University of Michigan Ann ArborMI48109 United States Department of Mechanical and Aerospace Engineering University of California San Diego La Jolla CA92093 United States Program in Materials Science and Engineering University of California San Diego La Jolla CA92093 United States

Unidirectional and backscattering-free propagation of sound waves is of fundamental interest in physics, and highly sought-after in engineering. Current strategies utilize topologically protected chiral edge modes in bandgaps, or complex mechanisms involving active constituents or nonlinearity. Here we propose a new class of passive, linear, one-way edge states based on spin-momentum locking of Rayleigh waves in two-dimensional media in the limit of vanishing bulk modulus, which provides 100% unidirectional and backscattering-free edge propagation at a broad range of frequencies instead of residing in gaps between bulk bands. We further show that such modes are characterized by a new topological winding number that is analogous to discrete angular momentum eigenvalues in quantum mechanics. These passive and backscattering-free edge waves have the potential to enable a new class of phononic devices in the form of lattices or continua that work in previously inaccessible frequency ranges. © 2023, CC BY.

关键词： Backscattering

Distinct Composition-Dependent Topological Hall Effect in Mn2-xZnxSb

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arXiv 2024年

作者： Nabi, Md Rafique Un Li, Yue te Velthuis, Suzanne G.E. Chhetri, Santosh Karki Upreti, Dinesh Basnet, Rabindra Acharya, Gokul Phatak, Charudatta Hu, Jin Department of Physics University of Arkansas FayettevilleAR72701 United States MonArk NSF Quantum Foundry University of Arkansas FayettevilleAR72701 United States Materials Science Division Argonne National Laboratory LemontIL60439 United States Department of Materials Science and Engineering Northwestern University EvanstonIL60208 United States Department of Chemistry áPhysics University of Arkansas at Pine Bluff Pine BluffAR71603 United States Materials Science and Engineering Program Institute for Nanoscience and Engineering University of Arkansas FayettevilleAR72701 United States

Spintronics, an evolving interdisciplinary field at the intersection of magnetism and electronics, explores innovative applications of electron charge and spin properties for advanced electronic devices. The topological Hall effect, a key component in spintronics, has gained significance due to emerging theories surrounding noncoplanar chiral spin textures. This study focuses on Mn2-xZnxSb, a material crystalizing in centrosymmetric space group with rich magnetic phases tunable by Zn contents. Through comprehensive magnetic and transport characterizations, we found that the high-Zn (χ>0.6) samples display THE which is enhanced with decreasing temperature, while THE in the low-Zn (χ © 2024, CC BY-NC-SA.

关键词： Manganese compounds

The connection between polymer collapse and the onset of jamming

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arXiv 2023年

作者： Grigas, Alex T. Fisher, Aliza Shattuck, Mark D. O’Hern, Corey S. Graduate Program in Computational Biology and Bioinformatics Yale University New HavenCT06520 United States Integrated Graduate Program in Physical and Engineering Biology Yale University New HavenCT06520 United States Department of Mechanical Engineering and Materials Science Yale University New HavenCT06520 United States Benjamin Levich Institute and Physics Department The City College of New York New YorkNY10031 United States Department of Physics Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States

Previous studies have shown that the interiors of proteins are densely packed, reaching packing fractions that are as large as those found for static packings of individual amino-acid-shaped particles. How can the interiors of proteins take on such high packing fractions given that amino acids are connected by peptide bonds and many amino acids are hydrophobic with attractive interactions? We investigate this question by comparing the structural and mechanical properties of collapsed attractive disk-shaped bead-spring polymers to those of three reference systems: static packings of repulsive disks, of attractive disks, and of repulsive disk-shaped bead-spring polymers. We show that attractive systems quenched to temperatures below the glass transition T Tg and static packings of both repulsive disks and bead-spring polymers possess similar interior packing fractions. Previous studies have shown that static packings of repulsive disks are isostatic at jamming onset, i.e. the number of contacts Nc matches the number of degrees of freedom, which strongly influences their mechanical properties. We find that repulsive polymers are hypostatic at jamming onset, but effectively isostatic when including quartic modes. While attractive disk and polymer packings are hyperstatic, we identify a definition for interparticle contacts for which they can also be considered as effectively isostatic. As a result, we show that the mechanical properties (e.g. scaling of the potential energy with excess contact number and low-frequency contribution to the density of vibrational modes) of weakly attractive disk and polymer packings are similar to those of isostatic repulsive disk and polymer packings. Our results demonstrate that static packings generated via attractive collapse or compression of repulsive particles possess similar structural and mechanical properties. © 2023, CC BY.

关键词： Amino acids

Top-Down Fabrication of Diamond Nanostructures

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SSRN

SSRN 2024年

作者： Biswas, Abhijit Li, Chenxi Pieshkov, Tymofii Mei, Zhaobo Xu, Mingfei Li, Tao Murukeshan, Jishnu Vajtai, Robert Zhao, Yuji Ajayan, Pulickel M. Department of Materials Science and NanoEngineering Rice University HoustonTX77005 United States Applied Physics Graduate Program Smalley-Curl Institute Rice University HoustonTX77005 United States Department of Electrical and Computer Engineering Rice University HoustonTX77005 United States

Diamond nanostructures can have exciting applications in electronics and thermal management, but their controlled fabrication can be challenging. Here, we present a top-down approach for the fabrication of diamond nanorod (DNR) clusters, via use of metal masks (Al, Ag, Au, and Cr) and reactive-ion etching (RIE). Prolonged RIE on Ag and Cr masks yields distinct etching profiles, and DNR clusters are selectively formed from Ag masks, with individual nanorods having dimensions of ~100 nm diameter and ~1.5 µm length. Detailed electron microscopy shows thin layer of amorphous carbon (a-C) around single crystalline DNR cores. Chemical analyses also show presence of oxygen on the surface of the DNRs. Fabrication of the DNR clusters with scalable top-down approach could lead to new nanodiamond-based applications. © 2024, The Authors. All rights reserved.

关键词： Nanorods

Preliminary study of development of students worksheet using creative problem based learning model in physics learning on senior high school 2

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Preliminary study of development of students worksheet using...

2nd International Conference on Research and Learning of physics, ICRLP 2019

作者： Prima, Novelia Usmeldi Study Program of Physics Education Universitas Negeri Padang Indonesia Electrical Engineering Department Universitas Negeri Padang Indonesia

The ability of students to think creatively in finding solutions to a problem is important in learning physics. However, teaching materials that used in school have not integrated learning model that can enhance students' creative thinking abilities. The solution to improve students' creative thinking skills is to develop worksheet using the Creative Problem-based Learning (CPBL) model in physics learning on Senior High School. To develop the worksheet, a preliminary study was conducted. This study used a descriptive method with the subjects of physics teacher in Senior High School at Padang. The instruments used are in the questionnaires and interview guidelines. Analyzing of the data is using descriptive analysis. The results showed that the performance analysis and the level of difficulty in learning were in the less category, and the student's creative thinking abilities in physics learning were in the very less category. © 2020 IOP Publishing Ltd. All rights reserved.

关键词： Students

Computational modeling of the physical features that influence breast cancer invasion into adipose tissue

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arXiv 2024年

作者： Zheng, Yitong Wang, Dong Beeghly, Garrett Fischbach, Claudia Shattuck, Mark D. O’Hern, Corey S. Department of Mechanical Engineering & Materials Science Yale University New HavenCT06520 United States Integrated Graduate Program in Physical and Engineering Biology Yale University New HavenCT06520 United States Nancy E. and Peter C. Meinig School of Biomedical Engineering Cornell University IthacaNY14853 United States Benjamin Levich Institute Physics Department City College of New York New YorkNY10031 United States Department of Physics Yale University New HavenCT06520 United States

Breast cancer invasion into adipose tissue strongly influences disease progression and metastasis. The degree of cancer cell invasion into adipose tissue depends on numerous biochemical and physical properties of cancer cells, adipocytes, and other key components of adipose tissue. We model breast cancer invasion into adipose tissue as a physical process by carrying out simulations of active, cohesive spherical particles (cancer cells) invading into confluent packings of deformable polyhedra (adipocytes). We quantify the degree of invasion by calculating the interfacial area At between cancer cells and adipocytes. We determine the long-time value of At versus the activity and strength of the cohesion between cancer cells, as well as mechanical properties of the adipocytes and extracellular matrix (ECM) in which the adipocytes are embedded. We show that the degree of invasion collapses onto a master curve by plotting it versus a dimensionless energy scale Ec, which grows linearly with mean-square fluctuations and persistence time of the cancer cell velocities, is inversely proportional to the pressure of the system, and has an offset that increases with the cancer cell cohesive energy. The condition, Ec 1, indicates that cancer cells will invade the adipose tissue, whereas for Ec 1, the cancer cells and adipocytes remain demixed. We also show that constraints on adipocyte positions by the ECM decrease At relative to that obtained for unconstrained adipocytes. Finally, spatial heterogeneity in structural and mechanical properties of the adipocytes in the presence of ECM impedes invasion relative to adipose tissue with uniform properties. © 2024, CC BY-NC-ND.

关键词： Cancer cells

Mechanical Plasticity of Cell Membranes Enhances Epithelial Wound Closure

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arXiv 2023年

作者： Ton, Andrew T. MacKeith, Arthur K. Shattuck, Mark D. O'Hern, Corey S. Department of Physics Yale University New HavenCT06520 United States Integrated Graduate Program in Physical and Engineering Biology Yale University New HavenCT06520 United States Department of Mechanical Engineering & Materials Science Yale University New HavenCT06520 United States Benjamin Levich Institute and Physics Department The City College of New York New YorkNY10031 United States Department of Applied Physics Yale University New HavenCT06520 United States

During epithelial wound healing, cell morphology near the healed wound and the healing rate vary strongly among different developmental stages even for a single species like Drosophila. We develop deformable particle (DP) model simulations to understand how variations in cell mechanics give rise to distinct wound closure phenotypes in the Drosophila embryonic ectoderm and larval wing disc epithelium. We find that plastic deformation of the cell membrane can generate large changes in cell shape consistent with wound closure in the embryonic ectoderm. Our results show that the embryonic ectoderm is best described by cell membranes with an elasto-plastic response, whereas the larval wing disc is best described by cell membranes with an exclusively elastic response. By varying the mechanical response of cell membranes in DP simulations, we recapitulate the wound closure behavior of both the embryonic ectoderm and the larval wing disc. © 2023, CC BY-NC-ND.

关键词： Cytology

Designing the pressure-dependent shear modulus using tessellated granular metamaterials

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arXiv 2023年

作者： Zhang, Jerry Wang, Dong Jin, Weiwei Xia, Annie Pashine, Nidhi Kramer-Bottiglio, Rebecca Shattuck, Mark D. O’Hern, Corey S. Department of Mechanical Engineering & Materials Science Yale University New HavenCT06520 United States Benjamin Levich Institute and Physics Department The City College of New York New YorkNY10031 United States Department of Physics Yale University New HavenCT06520 United States Department of Applied Physics Yale University New HavenCT06520 United States Integrated Graduate Program in Physical and Engineering Biology Yale University New HavenCT06520 United States

Jammed packings of granular materials display complex mechanical response. For example, the ensemble-averaged shear modulus 〈G〉 increases as a power-law in pressure p for static packings of soft spherical particles that can rearrange during compression. We seek to design granular materials with shear moduli that can either increase or decrease with pressure without particle rearrangements even in the large-system limit. To do this, we construct tessellated granular metamaterials by joining multiple particle-filled cells together. We focus on cells that contain a small number of bidisperse disks in two dimensions. We first study the mechanical properties of individual disk-filled cells with three types of boundaries: periodic boundary conditions (PBC), fixed-length walls (FXW), and flexible walls (FLW). Hypostatic jammed packings are found for cells with FLW, but not in cells with PBC and FXW, and they are stabilized by quartic modes of the dynamical matrix. The shear modulus of a single cell depends linearly on p. We find that the slope of the shear modulus with pressure, λc c > 0, as well as λc © 2023, CC BY.

关键词： Elastic moduli