Nanowerk June 9, 2023 Much of the hardware and sensors electronic devices rely on magnetoresistive random access memory (MRAM) and magnetic sensors. In magnetoresistive devices when the magnets are aligned, electrons can easily tunnel through the thin insulating barrier between them making the device efficient; when magnets are not aligned the device is less efficient due to higher resistance. Current tunnel magnetoresistive devices comprise magnesium oxide and iron-based magnetic alloys, like iron-cobalt. Iron-based alloys have a body-centered cubic crystal structure in ambient conditions and exhibit a huge tunnel magnetoresistance effect in devices with a rock salt-type magnesium oxide. Researchers in […]
Tag Archives: Materials science
The first 2D topological insulator that consists of a single element
Nanowerk May 16, 2023 The scattering of electrons at defects in 2D topological insulators is forbidden due to the unique topological protection mechanism which makes them more energy-efficient than current electronic materials. An international team of researchers (the Netherlands, Japan) made germanene was made from a single element. They melted germanium together with platinum. When the mixture cooled down, a tiny layer of germanium atoms arranged into a honeycomb lattice on top of the germanium-platinum alloy forming germanene. The conducting properties of the material could be switched ‘off’ by applying an electric field. This property is unique for a topological […]
Physicists discover ‘stacked pancakes of liquid magnetism’
Phys.org May 10, 2023 Magnetic frustrations and dimensionality play an important role in determining the nature of the magnetic long-range order and how it melts at temperatures above the ordering transition TN. A team of researchers in the US (Rice University, Ames National Laboratory, Iowa State University) used large-scale Monte Carlo simulations to study these phenomena in a class of frustrated Ising spin models in two spatial dimensions. They found that the melting of the magnetic long-range order into an isotropic gas like paramagnet proceeded via an intermediate stage where the classical spins remained anisotropically correlated. The correlated paramagnet existed […]
Supercomputers have revealed the giant ‘pillars of heat’ funneling diamonds upward from deep within Earth
Phys.org May 9, 2023 Most diamonds have been transported to Earth’s surface from depths between ~120 km and ~660 km by volatile-rich magmas called kimberlites. The reconstructed locations of kimberlites erupted in the past 320 million years have been shown to be correlated with seismically imaged large basal mantle structures at ~2,800 km depth. This correlation has been interpreted as requiring basal mantle structures to be stationary over time. However, the geodynamic process responsible for this correlation remains to be identified. Researchers in Australia developed global mantle convection models including a basal layer of dense material and driven by surface plate motions to […]
‘Gluing’ soft materials without glue
Science Daily May 3, 2023 Electroadhesion can involve chemical bonds, like ionic bonds, or more physical connections, like ensnaring polymer chains together. Researchers at the University of Maryland have demonstrated a universal, ‘electroadhesion’ technique that can adhere any soft materials to each other just by running electricity through them. They tested a gel in addition to three types of capsules made of alginate or chitosan that were either positively or negatively charged. When attached to graphite electrodes and exposed to a 10-V electric field for around 10 seconds, the oppositely charged materials stuck together strong enough to withstand gravity. By […]
New germanium-tin transistor as alternative to silicon
Nanowerk April 28, 2023 The continued downscaling of silicon CMOS technology presents challenges for achieving the required low power consumption. While high mobility channel materials hold promise for improved device performance at low power levels, a material system which enables both high mobility n-FETs and p-FETs, that is compatible with Si technology and can be readily integrated into existing fabrication lines is required. An international team of researchers (Germany, France, UK) has developed high performance, vertical nanowire gate-all-around FETs based on the GeSn-material system grown on Si. While the p-FET transconductance was increased to 850 µS/µm by exploiting the small band […]
Towards a sustainable superconductor technology with magnesium diboride super magnets
Phys.org May 1, 2023 Magnesium diboride (MgB2), a binary compound, behaves as a superconductor at a moderate temperature of around 39 K (-234°C). It can replace conventional low-temperature superconductors. However, it suffers from weak magnetic flux pinning. To enhance pinning, it is essential to tune the pinning centers in MgB2—the boundaries of grains or small crystals that constitute MgB2. An international team of researchers (Japan, Czech Republic) used high-energy ultra-sonication for refining coarse B powder dispersed in 2-propanol up to nanoscale sizes. Utrasonic vibrations imparted high speeds to B particles in the solvent, leading to collisions. The resulting friction and […]
Valley-transistor in two-dimensional materials – an ingredient for all-optical quantum technologies
Nanowerk April 23, 2023 Electrons in two-dimensional materials possess an additional quantum attribute, the valley pseudospin, labeled as K and K’—analogous to the spin up and spin down. Most of the research to achieve valley-selective excitations in valleytronics depends on resonant circularly polarized light with a given helicity. Not only acquiring valley-selective electron excitation but also switching the excitation from one valley to another is quintessential for bringing valleytronics-based technologies to reality. Researchers in India introduced a coherent control protocol to initiate valley-selective excitation, de-excitation, and switch the excitation from one valley to another on the fly within tens of […]
How one photon becomes four charge carriers
Phys.org April 14, 2023 In a usual solar cell, the energy of a single photon is transferred to two free charges in the material. However, a few molecular materials like pentacene are an exception and show conversion of one photon into four charges, instead. This excitation doubling, which is called exciton fission, could be extremely useful for high-efficiency photovoltaics, specifically to upgrade the dominant silicon-based technologies. An international team of researchers (Germany, Canada) used time- and angle-resolved photoemission spectroscopy to observe the primary step of singlet fission in crystalline pentacene. Their results indicated a charge-transfer mediated mechanism with a hybridization […]
Hydrogel-based flexible electronics
Nanowerk April 11, 2023 Although flexible electronics is an emerging field of research involving multiple disciplines, the broad applications of flexible electronics are still restricted due to several limitations, including high Young’s modulus, poor biocompatibility, and poor responsiveness. An international team of researchers (China, Singapore) reviewed the latest methods of synthesizing advanced functional hydrogels and the state-of-art applications of hydrogel-based flexible electronics. Hydrogel is a class of 3D crosslinked hydrated polymer networks, and its exceptional material properties render it as a promising candidate for the next generation of flexible electronics. They discussed the correlation between properties of the hydrogel and […]