Phys.org April 15, 2024 The stacking and twisting of atom-thin structures with matching crystal symmetry has provided a unique way to create new superlattice structures in which new properties emerge. An international team of researchers (Germany, Spain, USA – SLAC National Accelerator Laboratory, Stanford University) demonstrated a tailored light-wave-driven analogue to twisted layer stacking. Tailoring the spatial symmetry of the light waveform to that of the lattice of a hexagonal boron nitride monolayer and then twisting this waveform resulted in optical control of time-reversal symmetry breaking and the realization of the topological Haldane model in a laser-dressed two-dimensional insulating crystal. […]
Category Archives: Materials science
‘Surprising’ hidden activity of semiconductor material spotted by researchers
Science Daily April 11, 2024 Studies of electric field-driven insulator-to-metal (IMT) in the prototypical vanadium dioxide (VO2) thin-film channel devices are largely focused on the electrical and elastic responses of the films, but the response of the corresponding Titanium dioxide (TiO2) substrate is often overlooked. An international team of researchers (USA – Pennsylvania State University, Cornell University, Argonne National Laboratory, Germany) found that in-operando spatiotemporal imaging of the coupled elastodynamics using X-ray diffraction microscopy of a VO2 film channel device on TiO2 substrate the film channel bulged during the IMT instead shrinking as expected. A micron thick proximal layer in […]
This 3D printer can figure out how to print with an unknown material
Science Daily April 8, 2024 An international team of researchers (USA – MIT, National Institute of Standards and Technology, Greece) described a new method for the automatic generation of process parameters for fused filament fabrication (FFF) across varying machines and materials. They used an instrumented extruder to fit a function that maps nozzle pressures across varying flow rates and temperatures for a given machine and material configuration and developed a method to extract real parameters for flow rate and temperature using relative pressures and temperature offsets. Using their method they found process parameters, using one set of input parameters, across […]
New technique lets scientists create resistance-free electron channels
Science Daily April 9. 2024 Moiré systems made from stacked two-dimensional materials host correlated and topological states that can be electrically controlled with applied gate voltages. One prevalent form of topological state that can occur are Chern insulators that display a quantum anomalous Hall effect. An international team of researchers (USA – UC Berkeley, Lawrence Berkeley National Laboratory, Japan) manipulated Chern domains in an interaction-driven quantum anomalous Hall insulator made from twisted monolayer–bilayer graphene and observed chiral interface states at the boundary between different domains. By tuning the carrier concentration, they stabilized neighbouring domains of opposite Chern number that then […]
Physicists discover a novel quantum state in an elemental solid
Phys.org April 10, 2024 The nexus of topology and interactions yield important research directions. Using tunnelling microscopy, photoemission spectroscopy and a theoretical analysis an international team of researchers (USA – Princeton University, University of Alabama at Birmingham, Florida State University, Oak Ridge National laboratory, UK, Singapore, China, Switzerland) has shown a “hybrid” topological phase of matter in elemental-solid arsenic. They showed that arsenic features a conjoined strong and higher-order topology that stabilizes a hybrid topological phase. Measurements unraveled a unique geometry of topologically induced step-edge conduction channels. Using theoretical models, they showed that the existence of gapless step-edge states in […]
Unlocking exotic physics: Exploring graphene’s topological bands in super-moiré structures
Phys.org April 4, 2024 Moiré-pattern-based potential engineering has become an important way to explore exotic physics in a variety of two-dimensional condensed matter systems. An international team of researchers (Spain, Singapore) demonstrated theoretically that a single layer of graphene, when placed between two bulk boron nitride crystal substrates with the appropriate twist angles, could support a robust topological ultra flat band emerging as the second hole band. According to the researchers this is one of the simplest platforms to design and exploit topological flat bands… read more. TECHNICAL ARTICLE
Intelligent liquid
Nanowerk April 4, 2024 Traditionally the building blocks of metamaterials are arranged in fixed positions within a lattice structure. An international team of researchers (USA – Harvard University, Israel) showed that by mixing highly deformable spherical capsules into an incompressible fluid, it is possible to realize a ‘metafluid’ with programmable compressibility, optical behaviour, and viscosity. Experimentally and numerically, they demonstrated that the buckling of the shells endows the fluid with a highly nonlinear behaviour. They harnessed this behaviour to develop smart robotic systems, highly tunable logic gates and optical elements with switchable characteristics. They demonstrated that the collapse of the […]
New hydrogel can stretch to 15 times its original size
Phys.org March 29, 2024 Hyper elastic materials exhibit a nonlinear elastic response to large strains, whereas hydrogels typically possess a low elastic range due to the nonuniform cross-linking and limited chain segments among cross-links. An international team of researchers (USA, China) developed a hyperplastic hydrogel that possesses a broader elastic range by introducing a reversible pearl-necklace structure, in which beads are connected by strings. The subnanometric beads could efficiently unfold and refold under cyclic mechanical strains; thus, the hydrogel could rapidly recover after being stretched to an aerial strain of more than 10,000%. It could quickly heal from minor mechanical […]
Researchers determine structure of new metal tellurate material with potential uses in solar energy and more
Phys.org April 3, 2024 An international team of researchers (Austria, Sweden, Canada, Finland) grew crystals of CoTeO4 crystals by the application of chemical vapor transport reactions in closed silica ampoules, starting from polycrystalline material in a temperature gradient with TeCl4 as transport agent. Crystal structure analysis of CoTeO4 showed noticeable improvement over the statistical significance and accuracy of the previously reported structural model. CoTeO4 did not undergo a structural phase transition upon heating, but decomposed stepwise (Co2Te3O8 as intermediate phase) to Co3TeO6 as the only crystalline phase stable above 770 °C. Temperature-dependent magnetic susceptibility and dielectric measurements suggested antiferromagnetic ordering […]
Researchers discover dual topological phases in an intrinsic monolayer crystal
Phys.org April 2, 2024 Introducing electron correlations to a quantum spin Hall (QSH) insulator can lead to the emergence of a fractional topological insulator and other exotic time-reversal-symmetric topological order, not possible in quantum Hall and Chern insulator systems. An international team of researchers (USA – Boston College, Harvard University, UCLA, Texas A&M, University of Tennessee, MIT, Singapore, Japan, China, Canada) has found a new dual QSH insulator within the intrinsic monolayer crystal of TaIrTe4, arising from the interplay of its single-particle topology and density-tuned electron correlations. At charge neutrality, monolayer TaIrTe4 demonstrated the QSH insulator, manifesting enhanced nonlocal transport […]