Science Daily February 17, 2021 To investigate complex, functional, nanoscopic structures of semiconductor devices researchers in Germany have developed an imaging procedure using extreme ultraviolet coherence tomography. It is based on optical coherence tomography used in ophthalmology. They demonstrated the method at a laser-driven broadband extreme ultraviolet radiation source, based on high-harmonic generation. They showed that, besides nanoscopic axial resolution, the spectral reflectivity of all layers in a sample can be obtained using algorithmic phase reconstruction. This provides localized, spectroscopic, material-specific information of the sample. The method can be applied in semiconductor production, lithographic mask inspection, or quality control of multilayer […]
Tag Archives: Materials science
‘Magnetic graphene’ forms a new kind of magnetism
EurekAlert February 8, 2021 An international team of researchers ( UK, Uzbekistan, Russia, France, USA – Oak Ridge National Laboratory, Vietnam, South Korea, Czech Republic) was able to control the conductivity and magnetism of iron thiophosphate (FePS3) which undergoes a transition from an insulator to a metal when compressed. Using new techniques to measure the magnetic structure up to record-breaking high pressures, they found that magnetism survives, but gets modified into new forms, giving rise to new quantum properties in a new type of magnetic metal. The ‘spin’ of the electrons has been shown to be the source of magnetism. […]
Researchers construct molecular nanofibers that are stronger than steel
MIT News January 25, 2021 Small-molecule self-assembly is an established route for producing high-surface-area nanostructures with readily customizable chemistries and precise molecular organization. The whole structure falls apart when you remove water, particularly when any kind of external force is applied. An international team of researchers (USA – MIT, Argonne National Laboratory, France) has shown that a small-molecule platform, the aramid amphiphile overcomes these dynamic instabilities by incorporating a Kevlar-inspired domain into the molecular structure. Strong, anisotropic interactions between aramid amphiphiles suppress molecular exchange and elicit spontaneous self-assembly in water to form nanoribbons with lengths of up to 20 micrometres. […]
Solar material can ‘self-heal’ imperfections, new research shows
Phys.org January 27, 2021 Broken bonds introduced at extended defects in covalently bonded semiconductors generally introduce deep electronic states within the gap, negatively impacting performance for applications in electronics, photochemistry, and optoelectronics. Researchers in the UK found that Sb2Se3 and Sb2S3, which show exceptional promise for photovoltaic and photoelectrochemical applications, exhibit a remarkable ability to self‐heal broken bonds through structural reconstructions, thereby eliminating the associated deep electronic states. These materials appear intrinsically resilient to the formation of dangling bonds at extended defects, which should be advantageous for a wide range of applications. They could reduce costs and improve scalability of […]
Neither liquid nor solid
Science Daily January 5, 2021 Most experiments involving colloidal suspensions have relied on spherical colloids. Using polymer chemistry researchers in Germany manufactured small plastic particles, stretching, and cooling them until they achieved their ellipsoid forms and then placed them in a suitable solvent. They found that due to their distinct shapes their particles had orientation which gave rise to entirely new and previously unstudied kinds of complex behaviours. By changing particle concentrations in the suspensions, and tracking both the translational and rotational motion of the particles using confocal microscopy, they observed two competing glass transitions — a regular phase transformation […]
Scrambled supersolids: Soft form of a solid discovered
Science Daily January 4, 2021 An international team of researchers (Austria, Switzerland) created supersolids using ultracold quantum gases of highly magnetic lanthanide atoms. This state of matter is solid and liquid at the same time. Due to quantum effects, a very cold gas of atoms can spontaneously develop both a crystalline order of a solid crystal and particle flow like a superfluid quantum liquid. A dipolar supersolid can be imagined as a chain of quantum droplets which communicate with each other via a superfluid background bath. They found that if the superfluid bath between the droplets is drained by control […]
Metasurface enabled quantum edge detection
Phys.org December 29, 2020 Metasurfaces consisting of engineered dielectric or metallic structures provide unique solutions to realize exotic phenomena including negative refraction, achromatic focusing, electromagnetic cloaking, and so on. The intersection of metasurface and quantum optics may lead to new opportunities but is much less explored. An international team of researchers (China, USA – UC San Diego, Columbia University, Harvard University, Austria) proposed and experimentally demonstrated that a polarization-entangled photon source can be used to switch ON or OFF the optical edge detection mode in an imaging system based on a high-efficiency dielectric metasurface. This experiment enriches both fields of […]
UMBC team reveals possibilities of new one-atom-thick materials
EurekAlert December 15, 2020 Researchers at the University of Maryland demonstrated theoretically and experimentally that properties of two-dimensional group-III nitride semiconductors can be controlled by alloying. They found that by changing the alloying concentration, the band gap and exciton binding energies of each structure can be tuned accordingly, and for certain concentrations, a high thermoelectric performance was reported with strong dependence on the effective mass of the given alloyed monolayer. In addition, they explained contribution of each electron–hole (e-h) pair by investigating the e–h coupling strength projected on the electronic band structure. They found that the exciton binding energy decreases […]
Finetuning ‘twistronics’ of 2D crystals
Nanowerk December 4, 2020 Twistronics, tuning of twist angle controls the topology and electron interactions in 2D materials, is a rising research topic in physics in recent years. An international team of researchers (UK, China, Japan, Singapore) has developed a technique enabling twisted van der Waals heterostructures with dynamically tunable optical, mechanical, and electronic properties. Using this technique, they fabricated heterostructures where graphene is perfectly aligned with both top and bottom encapsulating layers of hexagonal boron nitride. The technique could be used in autonomous robotic manipulation of two-dimensional crystals to build van der Waals superlattices, which would allow accurate positioning, […]
Researchers control multiple wavelengths of light from a single source
Phys.org December 10, 2020 In carbon dots multi-wavelength emission can be stimulated under a single excitation source, enabling the simple and robust generation of white light from a single particle. Carbon dots also exhibit a concentration-dependent photoluminescence; however, this has not been fully understood. To understand this phenomenon and fully utilize the capabilities of carbon dots, researchers in South Korea posited and demonstrated that the dual-color-emissiveness is due to the interparticle distances between each carbon dot. They examined how the relative light intensity of the red and blue colors changed when varying the interparticle distances. They found that as the […]