Science Daily March 2, 2022 Researchers at the University of Chicago have introduced the concept of using topological defects in active matter to perform logic operations. When an extensile active stress in a nematic liquid crystal is turned on, +1/2 defects can self-propel, in analogy to electron transport under a voltage gradient. By relying on hydrodynamic simulations of active nematics, they demonstrated that patterns of activity, when combined with surfaces imparting certain orientations, can be used to control the formation and transport of +1/2 defects. They also showed that asymmetric high- and low-activity patterns can be used to create effective […]
Tag Archives: Advanced materials
Surprising semiconductor properties revealed with innovative new method
Phys.org March 1, 2022 An international team of researchers (USA – PNNL, UT Arlington) tested germanium in combination with a specialized thin crystalline film of lanthanum-strontium-zirconium-titanium-oxide (LSZTO) using hard X-ray photoelectron spectroscopy which can penetrate the material and generate information at the atomic level. They found that the oxygen atoms near the interface donate electrons to the LSZTO film, creating holes in the germanium within a few atomic layers of the interface. These specialized holes resulted in behavior that totally eclipsed the semiconducting properties of both n- and p-type germanium in the different samples they prepared. According to the researchers […]
Self-healing materials for robotics made from ‘jelly’ and salt
Science Daily February 18, 2022 There are numerous challenges in the deployment of wearable devices with soft sensing technologies due to their poor resilience, high energy consumption, and omnidirectional strain responsivity. Researchers in the UK have developed a versatile ionic gelatin-glycerol hydrogel for soft sensing applications. The device is inexpensive and easy to manufacture, self-healable at room temperature, can undergo strains of up to 454%, presents stability over long periods of time, and is biocompatible and biodegradable. The material is ideal for strain sensing applications, with a linear correlation coefficient R2 = 0.9971 and a pressure-insensitive conduction mechanism. The experimental results show […]
Versatile ‘nanocrystal gel’ could enable advances in energy, defense, and telecommunications
Science Daily February 18, 2022 By using reversibly bonded molecular linkers, gelation can be realized in nanocrystal gels that can be made into responsive and tunable materials. However, there is no experimental means to monitor linking leading to gelation. Researchers at UT Austin developed a metal coordination linkage with a distinct optical signature that allowed them to quantify linking in situ and establish structural and thermodynamic bases for assembly. Because of coupling between linked indium tin oxide nanocrystals, their infrared absorption shifted abruptly at a chemically tunable gelation temperature. They quantified bonding spectroscopically and used molecular simulation to understand temperature-dependent […]
Researchers create molecule that can pave way for mini transistors
Phys.org February 15, 2022 Organic molecules consist of aromatic benzene rings, flat rings made up of six carbon atoms, which do not change properties or shape if subjected to electric potential. An international team of researchers (Sweden, Denmark) developed a successful formula to design anti-aromatic hydrocarbons made up of rings with eight carbon atoms. When bent into a tub-shape, it becomes more robust and can both receive and relay electrons. If two electrons are injected into it the hydrocarbon flattens and goes from insulating to conducting—a function like that of a transistor switching from 0 to 1. The combination of […]
Scientists discover a mysterious transition in an electronic crystal
Phys.org February 7, 2022 Hysteresis underlies many phase transitions in solids, giving rise to exotic metastable states that are otherwise inaccessible. An international team of researchers (USA – MIT, UC Berkeley, Stanford University, SLAC Linear Accelerator Laboratory, Cornell University, Argonne National Laboratory, Clemson University, China, Russia, Germany) reported an unconventional hysteretic transition in a quasi-2D material, EuTe4. They observed that the hysteresis loop has a temperature width of more than 400 K, setting a record among crystalline solids. The transition has an origin distinct from known mechanisms, lying entirely within the incommensurate charge density wave (CDW) phase of EuTe4 with […]
Tiny electrical vortexes bridge gap between ferroelectric and ferromagnetic materials
EurekAlert February 9, 2022 An international team of researchers (UK, Ireland, USA – Argonne National Laboratory) created a thin film of the ferroelectric lead titanate sandwiched between layers of the ferromagnet strontium ruthenate, each about 4 nanometres thick. The structure of the combined layers revealed that the domains in the lead titanate were a complex topological structure of lines of vortexes, spinning alternately in different directions. Almost identical behaviour has also been seen in ferromagnets where it is known to be generated by the Dzyaloshinskii–Moriya interaction (DMi). According to the researchers the difference between ferromagnetism and ferroelectricity becomes less and […]
Physicists manipulate magnetism with light
Nanowerk January 28, 2022 The non-equilibrium driving of dressed quasiparticles offers a promising platform for realizing unconventional many-body phenomena and phases beyond thermodynamic equilibrium. An international team of researchers (USA – MIT, South Korea) achieved this in the van der Waals correlated insulator NiPS3 by photoexciting its newly discovered spin–orbit-entangled excitons that arise from Zhang-Rice states. By monitoring the time evolution of the terahertz conductivity, they observed the coexistence of itinerant carriers produced by exciton dissociation and a long-wavelength antiferromagnetic magnon that coherently processes in time. These results demonstrate the emergence of a transient metallic state that preserves long-range antiferromagnetism, […]
Impossible material made possible inside a graphene sandwich
Nanowerk January 20, 2022 So far, only a few dozen 2D crystals have been extracted from materials that exhibit a layered phase in ambient conditions, omitting entirely the large number of layered materials that may exist at other temperatures and pressures. An international team of researchers (Austria, Germany, Slovakia, Belgium, France) synthesized 2D cuprous iodide that was stabilized in a graphene sandwich, as the first example of a material that does not otherwise exist in normal laboratory conditions. It normally only occurs in layered form at elevated temperatures between 645 and 675 K. The synthesis utilizes the large interlayer spacing […]
A well-known iron-based magnet is also a potential quantum information material
Phys.org January 13, 2022 For quantum information processing the strongest-performing permanent magnets contain expensive rare-earth metals magnets. Researchers at the Iowa State University scanned vast number of iron-based permanent magnets and established that lanthanum-based hexaferrites show an advantage over conventional samarium-based hexaferrites. They identified LaFe12O19 as an excellent candidate for a gap magnet (iron-based permanent magnet). It is an excellent wide-bandgap semiconductor, can withstand higher voltages, frequencies, and temperatures. They discovered a new quantum state in this material, which strongly locks the magnetization along a fixed direction in the crystal, it could host other rare earths possessing nontrivial localized electronic […]