EurekAlert January 7, 2021 The electronic density of states (DOS) quantifies the distribution of the energy levels that can be occupied by electrons in a quasiparticle picture and is central to modern electronic structure theory and underpins the computation and interpretation of experimentally observable material properties such as optical absorption and electrical conductivity. An international team of researchers (Switzerland, UK) studied the configurations of silicon spanning a broad set of thermodynamic conditions, ranging from bulk structures to clusters and from semiconducting to metallic behavior and compared different approaches to represent the DOS, and the accuracy of predicting quantities such as […]
Category Archives: Materials science
Old silicon learns new tricks
Science Daily January 6, 2021 Using a combination of standard dry etching and chemical etching an international team of researchers (Japan, China) fabricated arrays of pyramid-shaped silicon nanostructures. An ultrathin layer of iron was deposited onto the silicon to impart unusual magnetic properties. The pyramids’ atomic-level orientation defined the orientation and thus the properties-of the overlaying iron. Epitaxial growth of iron enabled shape anisotropy of the nanofilm. The curve for the magnetization as a function of the magnetic field was rectangular-like shaped but with breaking points which were caused by asymmetric motion of magnetic vortex bound in pyramid apex. They […]
Stretching diamond for next-generation microelectronics
Science Daily December 31, 2020 An international team of researchers (Hong Kong, Taiwan, China, USA – UC Berkeley, Lawrence Berkeley National Laboratory, MIT) microfabricated single-crystalline diamond bridge structures with ~1 micrometer length by ~100 nanometer width and achieved sample-wide uniform elastic strains under uniaxial tensile loading at room temperature. They demonstrated deep elastic straining of diamond microbridge arrays. The ultra large, highly controllable elastic strains can fundamentally change the bulk band structures of diamond, including a substantial calculated bandgap reduction as much as ~2 electron volts. Their findings have shown the potential of strained diamonds as prime candidates for advanced […]
Artificial intelligence solves Schrödinger’s equation
Phys.org December 21, 2020 The goal of quantum chemistry is to predict chemical and physical properties of molecules based solely on the arrangement of their atoms in space, avoiding the need for resource-intensive and time-consuming laboratory experiments. In principle, this can be achieved by solving the Schrödinger equation. Up to now, it has been impossible to find an exact solution for arbitrary molecules that can be efficiently computed. To solve this problem researchers in Germany have proposed PauliNet, a deep-learning wavefunction ansatz that achieves nearly exact solutions of the electronic Schrödinger equation for molecules with up to 30 electrons. PauliNet […]
Ultra-thin designer materials unlock quantum phenomena
Science Daily December 17, 2020 Exotic states such as topological insulators, superconductors and quantum spin liquids are often challenging or impossible to create in a single material. The problem can be circumvented by deliberately selecting the combination of materials in heterostructures so that the desired physics emerges from interactions between the different components. An international team of researchers (Finland, Poland, Japan) used molecular-beam epitaxy to grow 2D islands of ferromagnetic chromium tribromide on superconducting niobium diselenide. They used low-temperature scanning tunneling microscopy and spectroscopy to reveal the signatures of one-dimensional Majorana edge modes. The fabricated 2D van der Waals heterostructure […]
Titanium atom that exists in two places at once in crystal to blame for unusual phenomenon
Science Daily December 3, 2020 The crystalline solid BaTiS3 (barium titanium sulfide) is terrible at conducting heat. An international team of researchers (Caltech, University of Southern California, Stanford University, Oak Ridge National Laboratory, Washington University, Wright Patterson AFB, Argonne National Laboratory, South Korea) found that a wayward titanium atom that exists in two places at the same time is to blame. It provides a fundamental atomic-level insight into an unusual thermal property that has been observed in several materials. The work is of particular interest to researchers who are exploring the potential use of crystalline solids with poor thermal conductivity […]
Researchers decipher structure of promising battery materials
MIT News November 23, 2020 MOFs’ extraordinary combination of porosity and conductivity opened the possibility of new applications in batteries, fuel cells, supercapacitors, electrocatalysts, and specialized chemical sensors. Because of the chemical bonds within the MOFs it has been difficult to grow crystals that were large enough for study to figure out their exact molecular structure and how it influences the material’s properties. An international team of researchers (USA – MIT, University of Oregon, University of Connecticut, Purdue University, China, Sweden) has found a way to control the growth of crystals of several kinds of MOFs enabling the team to […]
Topological mechanical metamaterials go beyond Newton’s third law
Phys.org November 19, 2020 An international team of researchers (Israel, Los Alamos) found a way to mimic non-Newtonian behavior in mechanical systems, and thereby develop a mechanical implementation for some of the more intractable topological quantum systems, which may offer fundamentally new insights into both the mechanical and quantum topological systems. The unit cells in a mechanical lattice are subjected to active feedback forces that are processed through autonomous controllers, pre-programmed to generate the desired local response in real-time. They demonstrated that the required topological phase, characterized by chiral edge modes, can be achieved in an analogous mechanical system only […]
Scientists Discover Exotic New Mineral Forged in The Furnace of a Russian Volcano
Science Alert November 18, 2020 The ‘Great Tolbachik Fissure Eruption’ of 1975–1976, and a second, lesser follow-up that took place between 2012–2013 opening rocky terrain to 130 unknown minerals which were identified. researchers in Russia have identified the latest one, petrovite, a sulfate mineral that takes shape as blue globular aggregates of tabular crystals, many holding gaseous inclusions. The copper atom in the crystal structure of petrovite has an unusual and rare coordination of seven oxygen atoms. At the chemical level, petrovite represents a new type of crystal structure. Its molecular framework – consisting of oxygen atoms, sodium sulphur and […]
Getting single-crystal diamond ready for electronics
Phys.org November 10, 2020 A limitation of silicon is that high temperatures damage which limits the operating speed of silicon-based electronics. Researchers in Japan fabricated a single-crystal diamond wafer and polished it using plasma-assisted polishing to be nearly atomically smooth. Common methods of polishing the surface are slow and damaging to the material. The polished surface was unaltered chemically. The only detected impurity was a small amount of nitrogen from the original wafer preparation. The procedure can help replace some of the silicon components of electronic devices with diamond…read more. Open Access TECHNICAL ARTICLE