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 […]
Tag Archives: Materials science
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 […]
Listen up, material!
Nanowerk March 27, 2023 Physical reservoir computing is a computational paradigm that enables spatiotemporal pattern recognition to be performed directly in matter. The use of physical matter leads the way toward energy-efficient devices capable of solving machine learning problems without having to build a system of millions of interconnected neurons. An international team of researchers (Germany, Belgium) proposed a high-performance “skyrmion mixture reservoir” that implemented the reservoir computing model with multidimensional inputs. This implementation solved spoken digit classification tasks with an overall model accuracy of 97.4% and a < 1% word error rate. According to the researchers due to the quality of […]
Using chemical exfoliation to produce superconducting tungsten disulfide ink
Phys.org March 23, 2023 Liquid-phase chemical exfoliation can achieve industry-scale production of 2D materials for a wide range of applications. However, because of their sensitivity to air and depreciation of physical performance many 2D materials cannot be used for practical application. An international team of researchers (USA – Princeton, Rutgers Universty, Germany) has developed a chemical exfoliation method to create a stable, aqueous, surfactant-free, superconducting ink containing phase-pure 1T”S2 monolayers that are isostructural to the air-sensitive topological insulator 1T′-WTe2. The printed film was metallic at room temperature and superconducting below 7.3 kelvin, showed strong anisotropic unconventional superconducting behavior with an […]
MIT physicists predict exotic new phenomena and give “recipe” for realizing them
MIT News March 17, 2023 van der Waals (vdW) heterostructures formed by 2D magnets and semiconductors have provided a fertile ground for fundamental science and spintronics. Through first-principles calculations researchers at MIT have found a proximity exchange splitting of 14 meV (equivalent to an effective Zeeman field of 120 T) in the vdW magnet-semiconductor heterostructure MoS 2/CrBr 3, leading to a 2D spin-polarized half-metal with carrier densities ranging up to 1013 cm−2. They explored the effect of large exchange coupling on the electronic band structure when the magnetic layer hosts chiral spin textures such as skyrmions. A flat Chern band […]
Scientists use lasers to recreate ‘twisted’ superconducting material
Phys.org March 21, 2023 In strong correlations and superconductivity in twisted-bilayer graphene the superposition of two twisted honeycomb lattices generating a moiré pattern is the key to the observed flat electronic bands, slow electron velocity and large density of states. An international team of researchers (USA – University of Chicago, China) demonstrated quantum simulation of superfluid to Mott insulator transition in twisted-bilayer square lattices based on atomic Bose–Einstein condensates loaded into spin-dependent optical lattices. The lattices are made of two sets of laser beams that independently address atoms in different spin states, which form the synthetic dimension accommodating the two […]
Surprise in the quantum world: Disorder leads to ferromagnetic topological insulator
Nanowerk March 21, 2023 The recent realizations of the quantum anomalous Hall effect in MnBi2Te4 and MnBi4Te7 benchmark the (MnBi2Te4)(Bi2Te3)n family as a promising hotbed for further quantum anomalous Hall effect improvements. However, the quantum anomalous Hall effect realization is complicated in MnBi2Te4 and MnBi4Te7 due to the substantial antiferromagnetic coupling between the septuple layers. Although ferromagnetic state can be stabilized by interlacing the septuple layers with an increasing number n of Bi2Te3 quintuple layers the mechanisms driving the FM state and the number of necessary quintuple layers are not understood, and the surface magnetism remains obscure. An international team […]
Shape memory achieved for nano-sized objects
Phys.org March 9, 2023 Magnetoelectric (ME) oxide materials can convert magnetic input into electric output and vice versa, making them excellent candidates for advanced sensing, data storage, and communication. However, their application has been limited to rigid devices due to their brittle nature. An international team of researcher (Switzerland, Germany, South Korea, Spain) has developed flexible ME oxide composite (BaTiO3/CoFe2O4) thin film nanostructures with distinct ME coupling coefficients. In contrast to rigid bulk counterparts, these ceramic nanostructures displayed a flexible behavior after being released from the substrate, and could be transferred onto a stretchable substrate such as polydimethylsiloxane. These ceramic […]
New method creates material that could create the next generation of solar cells
Science Daily February 24, 2023 Halide perovskites show ubiquitous presences in growing fields at both fundamental and applied levels. Discovery, investigation, and application of innovative perovskites are heavily dependent on the synthetic methodology in terms of time-/yield-/effort-/energy- efficiency. Conventional wet chemistry method provides the easiness for growing thin film samples but represents as an inefficient way for bulk crystal synthesis. A team of researchers in the US (Pennsylvania State University, U.S. Army CCDCAMC) has developed a universal solid state-based route for synthesizing high-quality perovskites by means of simultaneously applying both electric and mechanical stress fields during the synthesis, i.e., the […]